class Array

Parent:
Object
Included modules:
Enumerable

Arrays are ordered, integer-indexed collections of any object.

Array indexing starts at 0, as in C or Java. A negative index is assumed to be relative to the end of the array—that is, an index of -1 indicates the last element of the array, -2 is the next to last element in the array, and so on.

Creating Arrays

A new array can be created by using the literal constructor []. Arrays can contain different types of objects. For example, the array below contains an Integer, a String and a Float:

ary = [1, "two", 3.0] #=> [1, "two", 3.0]

An array can also be created by explicitly calling ::new with zero, one (the initial size of the Array) or two arguments (the initial size and a default object).

ary = Array.new    #=> []
Array.new(3)       #=> [nil, nil, nil]
Array.new(3, true) #=> [true, true, true]

Note that the second argument populates the array with references to the same object. Therefore, it is only recommended in cases when you need to instantiate arrays with natively immutable objects such as Symbols, numbers, true or false.

To create an array with separate objects a block can be passed instead. This method is safe to use with mutable objects such as hashes, strings or other arrays:

Array.new(4) { Hash.new }  #=> [{}, {}, {}, {}]
Array.new(4) {|i| i.to_s } #=> ["0", "1", "2", "3"]

This is also a quick way to build up multi-dimensional arrays:

empty_table = Array.new(3) { Array.new(3) }
#=> [[nil, nil, nil], [nil, nil, nil], [nil, nil, nil]]

An array can also be created by using the Array() method, provided by Kernel, which tries to call to_ary, then to_a on its argument.

Array({:a => "a", :b => "b"}) #=> [[:a, "a"], [:b, "b"]]

Example Usage

In addition to the methods it mixes in through the Enumerable module, the Array class has proprietary methods for accessing, searching and otherwise manipulating arrays.

Some of the more common ones are illustrated below.

Accessing Elements

Elements in an array can be retrieved using the #[] method. It can take a single integer argument (a numeric index), a pair of arguments (start and length) or a range. Negative indices start counting from the end, with -1 being the last element.

arr = [1, 2, 3, 4, 5, 6]
arr[2]    #=> 3
arr[100]  #=> nil
arr[-3]   #=> 4
arr[2, 3] #=> [3, 4, 5]
arr[1..4] #=> [2, 3, 4, 5]
arr[1..-3] #=> [2, 3, 4]

Another way to access a particular array element is by using the at method

arr.at(0) #=> 1

The slice method works in an identical manner to #[].

To raise an error for indices outside of the array bounds or else to provide a default value when that happens, you can use fetch.

arr = ['a', 'b', 'c', 'd', 'e', 'f']
arr.fetch(100) #=> IndexError: index 100 outside of array bounds: -6...6
arr.fetch(100, "oops") #=> "oops"

The special methods first and last will return the first and last elements of an array, respectively.

arr.first #=> 1
arr.last  #=> 6

To return the first n elements of an array, use take

arr.take(3) #=> [1, 2, 3]

drop does the opposite of take, by returning the elements after n elements have been dropped:

arr.drop(3) #=> [4, 5, 6]

Obtaining Information about an Array

Arrays keep track of their own length at all times. To query an array about the number of elements it contains, use length, count or size.

browsers = ['Chrome', 'Firefox', 'Safari', 'Opera', 'IE']
browsers.length #=> 5
browsers.count #=> 5

To check whether an array contains any elements at all

browsers.empty? #=> false

To check whether a particular item is included in the array

browsers.include?('Konqueror') #=> false

Adding Items to Arrays

Items can be added to the end of an array by using either push or <<

arr = [1, 2, 3, 4]
arr.push(5) #=> [1, 2, 3, 4, 5]
arr << 6    #=> [1, 2, 3, 4, 5, 6]

unshift will add a new item to the beginning of an array.

arr.unshift(0) #=> [0, 1, 2, 3, 4, 5, 6]

With insert you can add a new element to an array at any position.

arr.insert(3, 'apple')  #=> [0, 1, 2, 'apple', 3, 4, 5, 6]

Using the insert method, you can also insert multiple values at once:

arr.insert(3, 'orange', 'pear', 'grapefruit')
#=> [0, 1, 2, "orange", "pear", "grapefruit", "apple", 3, 4, 5, 6]

Removing Items from an Array

The method pop removes the last element in an array and returns it:

arr =  [1, 2, 3, 4, 5, 6]
arr.pop #=> 6
arr #=> [1, 2, 3, 4, 5]

To retrieve and at the same time remove the first item, use shift:

arr.shift #=> 1
arr #=> [2, 3, 4, 5]

To delete an element at a particular index:

arr.delete_at(2) #=> 4
arr #=> [2, 3, 5]

To delete a particular element anywhere in an array, use delete:

arr = [1, 2, 2, 3]
arr.delete(2) #=> 2
arr #=> [1,3]

A useful method if you need to remove nil values from an array is compact:

arr = ['foo', 0, nil, 'bar', 7, 'baz', nil]
arr.compact  #=> ['foo', 0, 'bar', 7, 'baz']
arr          #=> ['foo', 0, nil, 'bar', 7, 'baz', nil]
arr.compact! #=> ['foo', 0, 'bar', 7, 'baz']
arr          #=> ['foo', 0, 'bar', 7, 'baz']

Another common need is to remove duplicate elements from an array.

It has the non-destructive uniq, and destructive method uniq!

arr = [2, 5, 6, 556, 6, 6, 8, 9, 0, 123, 556]
arr.uniq #=> [2, 5, 6, 556, 8, 9, 0, 123]

Iterating over Arrays

Like all classes that include the Enumerable module, Array has an each method, which defines what elements should be iterated over and how. In case of Array's each, all elements in the Array instance are yielded to the supplied block in sequence.

Note that this operation leaves the array unchanged.

arr = [1, 2, 3, 4, 5]
arr.each { |a| print a -= 10, " " }
# prints: -9 -8 -7 -6 -5
#=> [1, 2, 3, 4, 5]

Another sometimes useful iterator is reverse_each which will iterate over the elements in the array in reverse order.

words = %w[first second third fourth fifth sixth]
str = ""
words.reverse_each { |word| str += "#{word} " }
p str #=> "sixth fifth fourth third second first "

The map method can be used to create a new array based on the original array, but with the values modified by the supplied block:

arr.map { |a| 2*a }   #=> [2, 4, 6, 8, 10]
arr                   #=> [1, 2, 3, 4, 5]
arr.map! { |a| a**2 } #=> [1, 4, 9, 16, 25]
arr                   #=> [1, 4, 9, 16, 25]

Selecting Items from an Array

Elements can be selected from an array according to criteria defined in a block. The selection can happen in a destructive or a non-destructive manner. While the destructive operations will modify the array they were called on, the non-destructive methods usually return a new array with the selected elements, but leave the original array unchanged.

Non-destructive Selection

arr = [1, 2, 3, 4, 5, 6]
arr.select { |a| a > 3 }     #=> [4, 5, 6]
arr.reject { |a| a < 3 }     #=> [3, 4, 5, 6]
arr.drop_while { |a| a < 4 } #=> [4, 5, 6]
arr                          #=> [1, 2, 3, 4, 5, 6]

Destructive Selection

select! and reject! are the corresponding destructive methods to select and reject

Similar to select vs. reject, delete_if and keep_if have the exact opposite result when supplied with the same block:

arr.delete_if { |a| a < 4 } #=> [4, 5, 6]
arr                         #=> [4, 5, 6]

arr = [1, 2, 3, 4, 5, 6]
arr.keep_if { |a| a < 4 } #=> [1, 2, 3]
arr                       #=> [1, 2, 3]

Public Class Methods

[](*args) Show source
static VALUE
rb_ary_s_create(int argc, VALUE *argv, VALUE klass)
{
    VALUE ary = ary_new(klass, argc);
    if (argc > 0 && argv) {
        ary_memcpy(ary, 0, argc, argv);
        ARY_SET_LEN(ary, argc);
    }

    return ary;
}

Returns a new array populated with the given objects.

Array.[]( 1, 'a', /^A/ ) # => [1, "a", /^A/]
Array[ 1, 'a', /^A/ ]    # => [1, "a", /^A/]
[ 1, 'a', /^A/ ]         # => [1, "a", /^A/]
new(size=0, default=nil) Show source
new(array)
new(size) {|index| block }
static VALUE
rb_ary_initialize(int argc, VALUE *argv, VALUE ary)
{
    long len;
    VALUE size, val;

    rb_ary_modify(ary);
    if (argc == 0) {
        if (ARY_OWNS_HEAP_P(ary) && RARRAY_CONST_PTR(ary) != 0) {
            ruby_sized_xfree((void *)RARRAY_CONST_PTR(ary), ARY_HEAP_SIZE(ary));
        }
        rb_ary_unshare_safe(ary);
        FL_SET_EMBED(ary);
        ARY_SET_EMBED_LEN(ary, 0);
        if (rb_block_given_p()) {
            rb_warning("given block not used");
        }
        return ary;
    }
    rb_scan_args(argc, argv, "02", &size, &val);
    if (argc == 1 && !FIXNUM_P(size)) {
        val = rb_check_array_type(size);
        if (!NIL_P(val)) {
            rb_ary_replace(ary, val);
            return ary;
        }
    }

    len = NUM2LONG(size);
    /* NUM2LONG() may call size.to_int, ary can be frozen, modified, etc */
    if (len < 0) {
        rb_raise(rb_eArgError, "negative array size");
    }
    if (len > ARY_MAX_SIZE) {
        rb_raise(rb_eArgError, "array size too big");
    }
    /* recheck after argument conversion */
    rb_ary_modify(ary);
    ary_resize_capa(ary, len);
    if (rb_block_given_p()) {
        long i;

        if (argc == 2) {
            rb_warn("block supersedes default value argument");
        }
        for (i=0; i<len; i++) {
            rb_ary_store(ary, i, rb_yield(LONG2NUM(i)));
            ARY_SET_LEN(ary, i + 1);
        }
    }
    else {
        ary_memfill(ary, 0, len, val);
        ARY_SET_LEN(ary, len);
    }
    return ary;
}

Returns a new array.

In the first form, if no arguments are sent, the new array will be empty. When a size and an optional default are sent, an array is created with size copies of default. Take notice that all elements will reference the same object default.

The second form creates a copy of the array passed as a parameter (the array is generated by calling #to_ary on the parameter).

first_array = ["Matz", "Guido"]

second_array = Array.new(first_array) #=> ["Matz", "Guido"]

first_array.equal? second_array       #=> false

In the last form, an array of the given size is created. Each element in this array is created by passing the element's index to the given block and storing the return value.

Array.new(3){ |index| index ** 2 }
# => [0, 1, 4]

Common gotchas

When sending the second parameter, the same object will be used as the value for all the array elements:

a = Array.new(2, Hash.new)
# => [{}, {}]

a[0]['cat'] = 'feline'
a # => [{"cat"=>"feline"}, {"cat"=>"feline"}]

a[1]['cat'] = 'Felix'
a # => [{"cat"=>"Felix"}, {"cat"=>"Felix"}]

Since all the Array elements store the same hash, changes to one of them will affect them all.

If multiple copies are what you want, you should use the block version which uses the result of that block each time an element of the array needs to be initialized:

a = Array.new(2) { Hash.new }
a[0]['cat'] = 'feline'
a # => [{"cat"=>"feline"}, {}]
try_convert(obj) → array or nil Show source
static VALUE
rb_ary_s_try_convert(VALUE dummy, VALUE ary)
{
    return rb_check_array_type(ary);
}

Tries to convert obj into an array, using to_ary method. Returns the converted array or nil if obj cannot be converted for any reason. This method can be used to check if an argument is an array.

Array.try_convert([1])   #=> [1]
Array.try_convert("1")   #=> nil

if tmp = Array.try_convert(arg)
  # the argument is an array
elsif tmp = String.try_convert(arg)
  # the argument is a string
end

Public Instance Methods

ary & other_ary → new_ary Show source
static VALUE
rb_ary_and(VALUE ary1, VALUE ary2)
{
    VALUE hash, ary3, v;
    st_table *table;
    st_data_t vv;
    long i;

    ary2 = to_ary(ary2);
    ary3 = rb_ary_new();
    if (RARRAY_LEN(ary2) == 0) return ary3;
    hash = ary_make_hash(ary2);
    table = rb_hash_tbl_raw(hash);

    for (i=0; i<RARRAY_LEN(ary1); i++) {
        v = RARRAY_AREF(ary1, i);
        vv = (st_data_t)v;
        if (st_delete(table, &vv, 0)) {
            rb_ary_push(ary3, v);
        }
    }
    ary_recycle_hash(hash);

    return ary3;
}

Set Intersection — Returns a new array containing elements common to the two arrays, excluding any duplicates. The order is preserved from the original array.

It compares elements using their hash and eql? methods for efficiency.

[ 1, 1, 3, 5 ] & [ 1, 2, 3 ]                 #=> [ 1, 3 ]
[ 'a', 'b', 'b', 'z' ] & [ 'a', 'b', 'c' ]   #=> [ 'a', 'b' ]

See also #uniq.

ary * int → new_ary Show source
ary * str → new_string
static VALUE
rb_ary_times(VALUE ary, VALUE times)
{
    VALUE ary2, tmp;
    const VALUE *ptr;
    long t, len;

    tmp = rb_check_string_type(times);
    if (!NIL_P(tmp)) {
        return rb_ary_join(ary, tmp);
    }

    len = NUM2LONG(times);
    if (len == 0) {
        ary2 = ary_new(rb_obj_class(ary), 0);
        goto out;
    }
    if (len < 0) {
        rb_raise(rb_eArgError, "negative argument");
    }
    if (ARY_MAX_SIZE/len < RARRAY_LEN(ary)) {
        rb_raise(rb_eArgError, "argument too big");
    }
    len *= RARRAY_LEN(ary);

    ary2 = ary_new(rb_obj_class(ary), len);
    ARY_SET_LEN(ary2, len);

    ptr = RARRAY_CONST_PTR(ary);
    t = RARRAY_LEN(ary);
    if (0 < t) {
        ary_memcpy(ary2, 0, t, ptr);
        while (t <= len/2) {
            ary_memcpy(ary2, t, t, RARRAY_CONST_PTR(ary2));
            t *= 2;
        }
        if (t < len) {
            ary_memcpy(ary2, t, len-t, RARRAY_CONST_PTR(ary2));
        }
    }
  out:
    OBJ_INFECT(ary2, ary);

    return ary2;
}

Repetition — With a String argument, equivalent to ary.join(str).

Otherwise, returns a new array built by concatenating the int copies of self.

[ 1, 2, 3 ] * 3    #=> [ 1, 2, 3, 1, 2, 3, 1, 2, 3 ]
[ 1, 2, 3 ] * ","  #=> "1,2,3"
ary + other_ary → new_ary Show source
VALUE
rb_ary_plus(VALUE x, VALUE y)
{
    VALUE z;
    long len, xlen, ylen;

    y = to_ary(y);
    xlen = RARRAY_LEN(x);
    ylen = RARRAY_LEN(y);
    len = xlen + ylen;
    z = rb_ary_new2(len);

    ary_memcpy(z, 0, xlen, RARRAY_CONST_PTR(x));
    ary_memcpy(z, xlen, ylen, RARRAY_CONST_PTR(y));
    ARY_SET_LEN(z, len);
    return z;
}

Concatenation — Returns a new array built by concatenating the two arrays together to produce a third array.

[ 1, 2, 3 ] + [ 4, 5 ]    #=> [ 1, 2, 3, 4, 5 ]
a = [ "a", "b", "c" ]
c = a + [ "d", "e", "f" ]
c                         #=> [ "a", "b", "c", "d", "e", "f" ]
a                         #=> [ "a", "b", "c" ]

Note that

x += y

is the same as

x = x + y

This means that it produces a new array. As a consequence, repeated use of += on arrays can be quite inefficient.

See also #concat.

ary - other_ary → new_ary Show source
static VALUE
rb_ary_diff(VALUE ary1, VALUE ary2)
{
    VALUE ary3;
    VALUE hash;
    long i;

    hash = ary_make_hash(to_ary(ary2));
    ary3 = rb_ary_new();

    for (i=0; i<RARRAY_LEN(ary1); i++) {
        if (st_lookup(rb_hash_tbl_raw(hash), RARRAY_AREF(ary1, i), 0)) continue;
        rb_ary_push(ary3, rb_ary_elt(ary1, i));
    }
    ary_recycle_hash(hash);
    return ary3;
}

Array Difference

Returns a new array that is a copy of the original array, removing any items that also appear in other_ary. The order is preserved from the original array.

It compares elements using their hash and eql? methods for efficiency.

[ 1, 1, 2, 2, 3, 3, 4, 5 ] - [ 1, 2, 4 ]  #=>  [ 3, 3, 5 ]

If you need set-like behavior, see the library class Set.

ary << obj → ary Show source
VALUE
rb_ary_push(VALUE ary, VALUE item)
{
    long idx = RARRAY_LEN(ary);
    VALUE target_ary = ary_ensure_room_for_push(ary, 1);
    RARRAY_PTR_USE(ary, ptr, {
        RB_OBJ_WRITE(target_ary, &ptr[idx], item);
    });
    ARY_SET_LEN(ary, idx + 1);
    return ary;
}

Append—Pushes the given object on to the end of this array. This expression returns the array itself, so several appends may be chained together.

[ 1, 2 ] << "c" << "d" << [ 3, 4 ]
        #=>  [ 1, 2, "c", "d", [ 3, 4 ] ]
ary <=> other_ary → -1, 0, +1 or nil Show source
VALUE
rb_ary_cmp(VALUE ary1, VALUE ary2)
{
    long len;
    VALUE v;

    ary2 = rb_check_array_type(ary2);
    if (NIL_P(ary2)) return Qnil;
    if (ary1 == ary2) return INT2FIX(0);
    v = rb_exec_recursive_paired(recursive_cmp, ary1, ary2, ary2);
    if (v != Qundef) return v;
    len = RARRAY_LEN(ary1) - RARRAY_LEN(ary2);
    if (len == 0) return INT2FIX(0);
    if (len > 0) return INT2FIX(1);
    return INT2FIX(-1);
}

Comparison — Returns an integer (-1, 0, or +1) if this array is less than, equal to, or greater than other_ary.

Each object in each array is compared (using the <=> operator).

Arrays are compared in an “element-wise” manner; the first element of ary is compared with the first one of other_ary using the <=> operator, then each of the second elements, etc… As soon as the result of any such comparison is non zero (i.e. the two corresponding elements are not equal), that result is returned for the whole array comparison.

If all the elements are equal, then the result is based on a comparison of the array lengths. Thus, two arrays are “equal” according to Array#<=> if, and only if, they have the same length and the value of each element is equal to the value of the corresponding element in the other array.

nil is returned if the other_ary is not an array or if the comparison of two elements returned nil.

[ "a", "a", "c" ]    <=> [ "a", "b", "c" ]   #=> -1
[ 1, 2, 3, 4, 5, 6 ] <=> [ 1, 2 ]            #=> +1
[ 1, 2 ]             <=> [ 1, :two ]         #=> nil
ary == other_ary → bool Show source
static VALUE
rb_ary_equal(VALUE ary1, VALUE ary2)
{
    if (ary1 == ary2) return Qtrue;
    if (!RB_TYPE_P(ary2, T_ARRAY)) {
        if (!rb_respond_to(ary2, idTo_ary)) {
            return Qfalse;
        }
        return rb_equal(ary2, ary1);
    }
    if (RARRAY_LEN(ary1) != RARRAY_LEN(ary2)) return Qfalse;
    if (RARRAY_CONST_PTR(ary1) == RARRAY_CONST_PTR(ary2)) return Qtrue;
    return rb_exec_recursive_paired(recursive_equal, ary1, ary2, ary2);
}

Equality — Two arrays are equal if they contain the same number of elements and if each element is equal to (according to Object#==) the corresponding element in other_ary.

[ "a", "c" ]    == [ "a", "c", 7 ]     #=> false
[ "a", "c", 7 ] == [ "a", "c", 7 ]     #=> true
[ "a", "c", 7 ] == [ "a", "d", "f" ]   #=> false
ary[index] → obj or nil Show source
ary[start, length] → new_ary or nil
ary[range] → new_ary or nil
slice(index) → obj or nil
slice(start, length) → new_ary or nil
slice(range) → new_ary or nil
VALUE
rb_ary_aref(int argc, const VALUE *argv, VALUE ary)
{
    VALUE arg;
    long beg, len;

    if (argc == 2) {
        beg = NUM2LONG(argv[0]);
        len = NUM2LONG(argv[1]);
        if (beg < 0) {
            beg += RARRAY_LEN(ary);
        }
        return rb_ary_subseq(ary, beg, len);
    }
    if (argc != 1) {
        rb_scan_args(argc, argv, "11", NULL, NULL);
    }
    arg = argv[0];
    /* special case - speeding up */
    if (FIXNUM_P(arg)) {
        return rb_ary_entry(ary, FIX2LONG(arg));
    }
    /* check if idx is Range */
    switch (rb_range_beg_len(arg, &beg, &len, RARRAY_LEN(ary), 0)) {
      case Qfalse:
        break;
      case Qnil:
        return Qnil;
      default:
        return rb_ary_subseq(ary, beg, len);
    }
    return rb_ary_entry(ary, NUM2LONG(arg));
}

Element Reference — Returns the element at index, or returns a subarray starting at the start index and continuing for length elements, or returns a subarray specified by range of indices.

Negative indices count backward from the end of the array (-1 is the last element). For start and range cases the starting index is just before an element. Additionally, an empty array is returned when the starting index for an element range is at the end of the array.

Returns nil if the index (or starting index) are out of range.

a = [ "a", "b", "c", "d", "e" ]
a[2] +  a[0] + a[1]    #=> "cab"
a[6]                   #=> nil
a[1, 2]                #=> [ "b", "c" ]
a[1..3]                #=> [ "b", "c", "d" ]
a[4..7]                #=> [ "e" ]
a[6..10]               #=> nil
a[-3, 3]               #=> [ "c", "d", "e" ]
# special cases
a[5]                   #=> nil
a[6, 1]                #=> nil
a[5, 1]                #=> []
a[5..10]               #=> []
ary[index] = obj → obj Show source
ary[start, length] = obj or other_ary or nil → obj or other_ary or nil
ary[range] = obj or other_ary or nil → obj or other_ary or nil
static VALUE
rb_ary_aset(int argc, VALUE *argv, VALUE ary)
{
    long offset, beg, len;

    if (argc == 3) {
        rb_ary_modify_check(ary);
        beg = NUM2LONG(argv[0]);
        len = NUM2LONG(argv[1]);
        rb_ary_splice(ary, beg, len, argv[2]);
        return argv[2];
    }
    rb_check_arity(argc, 2, 2);
    rb_ary_modify_check(ary);
    if (FIXNUM_P(argv[0])) {
        offset = FIX2LONG(argv[0]);
        goto fixnum;
    }
    if (rb_range_beg_len(argv[0], &beg, &len, RARRAY_LEN(ary), 1)) {
        /* check if idx is Range */
        rb_ary_splice(ary, beg, len, argv[1]);
        return argv[1];
    }

    offset = NUM2LONG(argv[0]);
fixnum:
    rb_ary_store(ary, offset, argv[1]);
    return argv[1];
}

Element Assignment — Sets the element at index, or replaces a subarray from the start index for length elements, or replaces a subarray specified by the range of indices.

If indices are greater than the current capacity of the array, the array grows automatically. Elements are inserted into the array at start if length is zero.

Negative indices will count backward from the end of the array. For start and range cases the starting index is just before an element.

An IndexError is raised if a negative index points past the beginning of the array.

See also #push, and #unshift.

a = Array.new
a[4] = "4";                 #=> [nil, nil, nil, nil, "4"]
a[0, 3] = [ 'a', 'b', 'c' ] #=> ["a", "b", "c", nil, "4"]
a[1..2] = [ 1, 2 ]          #=> ["a", 1, 2, nil, "4"]
a[0, 2] = "?"               #=> ["?", 2, nil, "4"]
a[0..2] = "A"               #=> ["A", "4"]
a[-1]   = "Z"               #=> ["A", "Z"]
a[1..-1] = nil              #=> ["A", nil]
a[1..-1] = []               #=> ["A"]
a[0, 0] = [ 1, 2 ]          #=> [1, 2, "A"]
a[3, 0] = "B"               #=> [1, 2, "A", "B"]
abbrev(pattern = nil) Show source
# File lib/abbrev.rb, line 128
def abbrev(pattern = nil)
  Abbrev::abbrev(self, pattern)
end

Calculates the set of unambiguous abbreviations for the strings in self.

require 'abbrev'
%w{ car cone }.abbrev
#=> {"car"=>"car", "ca"=>"car", "cone"=>"cone", "con"=>"cone", "co"=>"cone"}

The optional pattern parameter is a pattern or a string. Only input strings that match the pattern or start with the string are included in the output hash.

%w{ fast boat day }.abbrev(/^.a/)
#=> {"fast"=>"fast", "fas"=>"fast", "fa"=>"fast", "day"=>"day", "da"=>"day"}

Abbrev.abbrev(%w{car box cone}, "ca")
#=> {"car"=>"car", "ca"=>"car"}

See also Abbrev#abbrev

any? [{ |obj| block }] → true or false Show source
static VALUE
rb_ary_any_p(VALUE ary)
{
    long i, len = RARRAY_LEN(ary);
    const VALUE *ptr = RARRAY_CONST_PTR(ary);

    if (!len) return Qfalse;
    if (!rb_block_given_p()) {
        for (i = 0; i < len; ++i) if (RTEST(ptr[i])) return Qtrue;
    }
    else {
        for (i = 0; i < RARRAY_LEN(ary); ++i) {
            if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) return Qtrue;
        }
    }
    return Qfalse;
}

See also Enumerable#any?

assoc(obj) → new_ary or nil Show source
VALUE
rb_ary_assoc(VALUE ary, VALUE key)
{
    long i;
    VALUE v;

    for (i = 0; i < RARRAY_LEN(ary); ++i) {
        v = rb_check_array_type(RARRAY_AREF(ary, i));
        if (!NIL_P(v) && RARRAY_LEN(v) > 0 &&
            rb_equal(RARRAY_AREF(v, 0), key))
            return v;
    }
    return Qnil;
}

Searches through an array whose elements are also arrays comparing obj with the first element of each contained array using obj.==.

Returns the first contained array that matches (that is, the first associated array), or nil if no match is found.

See also #rassoc

s1 = [ "colors", "red", "blue", "green" ]
s2 = [ "letters", "a", "b", "c" ]
s3 = "foo"
a  = [ s1, s2, s3 ]
a.assoc("letters")  #=> [ "letters", "a", "b", "c" ]
a.assoc("foo")      #=> nil
at(index) → obj or nil Show source
static VALUE
rb_ary_at(VALUE ary, VALUE pos)
{
    return rb_ary_entry(ary, NUM2LONG(pos));
}

Returns the element at index. A negative index counts from the end of self. Returns nil if the index is out of range. See also #[].

a = [ "a", "b", "c", "d", "e" ]
a.at(0)     #=> "a"
a.at(-1)    #=> "e"
bsearch {|x| block } → elem Show source
static VALUE
rb_ary_bsearch(VALUE ary)
{
    long low = 0, high = RARRAY_LEN(ary), mid;
    int smaller = 0, satisfied = 0;
    VALUE v, val;

    RETURN_ENUMERATOR(ary, 0, 0);
    while (low < high) {
        mid = low + ((high - low) / 2);
        val = rb_ary_entry(ary, mid);
        v = rb_yield(val);
        if (FIXNUM_P(v)) {
            if (FIX2INT(v) == 0) return val;
            smaller = FIX2INT(v) < 0;
        }
        else if (v == Qtrue) {
            satisfied = 1;
            smaller = 1;
        }
        else if (v == Qfalse || v == Qnil) {
            smaller = 0;
        }
        else if (rb_obj_is_kind_of(v, rb_cNumeric)) {
            const VALUE zero = INT2FIX(0);
            switch (rb_cmpint(rb_funcallv(v, id_cmp, 1, &zero), v, INT2FIX(0))) {
                case 0: return val;
                case 1: smaller = 1; break;
                case -1: smaller = 0;
            }
        }
        else {
            rb_raise(rb_eTypeError, "wrong argument type %s"
                " (must be numeric, true, false or nil)",
                rb_obj_classname(v));
        }
        if (smaller) {
            high = mid;
        }
        else {
            low = mid + 1;
        }
    }
    if (low == RARRAY_LEN(ary)) return Qnil;
    if (!satisfied) return Qnil;
    return rb_ary_entry(ary, low);
}

By using binary search, finds a value from this array which meets the given condition in O(log n) where n is the size of the array.

You can use this method in two use cases: a find-minimum mode and a find-any mode. In either case, the elements of the array must be monotone (or sorted) with respect to the block.

In find-minimum mode (this is a good choice for typical use case), the block must return true or false, and there must be an index i (0 <= i <= ary.size) so that:

  • the block returns false for any element whose index is less than i, and

  • the block returns true for any element whose index is greater than or equal to i.

This method returns the i-th element. If i is equal to ary.size, it returns nil.

ary = [0, 4, 7, 10, 12]
ary.bsearch {|x| x >=   4 } #=> 4
ary.bsearch {|x| x >=   6 } #=> 7
ary.bsearch {|x| x >=  -1 } #=> 0
ary.bsearch {|x| x >= 100 } #=> nil

In find-any mode (this behaves like libc's bsearch(3)), the block must return a number, and there must be two indices i and j (0 <= i <= j <= ary.size) so that:

  • the block returns a positive number for ary if 0 <= k < i,

  • the block returns zero for ary if i <= k < j, and

  • the block returns a negative number for ary if j <= k < ary.size.

Under this condition, this method returns any element whose index is within i…j. If i is equal to j (i.e., there is no element that satisfies the block), this method returns nil.

ary = [0, 4, 7, 10, 12]
# try to find v such that 4 <= v < 8
ary.bsearch {|x| 1 - x / 4 } #=> 4 or 7
# try to find v such that 8 <= v < 10
ary.bsearch {|x| 4 - x / 2 } #=> nil

You must not mix the two modes at a time; the block must always return either true/false, or always return a number. It is undefined which value is actually picked up at each iteration.

clear → ary Show source
VALUE
rb_ary_clear(VALUE ary)
{
    rb_ary_modify_check(ary);
    ARY_SET_LEN(ary, 0);
    if (ARY_SHARED_P(ary)) {
        if (!ARY_EMBED_P(ary)) {
            rb_ary_unshare(ary);
            FL_SET_EMBED(ary);
        }
    }
    else if (ARY_DEFAULT_SIZE * 2 < ARY_CAPA(ary)) {
        ary_resize_capa(ary, ARY_DEFAULT_SIZE * 2);
    }
    return ary;
}

Removes all elements from self.

a = [ "a", "b", "c", "d", "e" ]
a.clear    #=> [ ]
collect { |item| block } → new_ary Show source
collect → Enumerator
static VALUE
rb_ary_collect(VALUE ary)
{
    long i;
    VALUE collect;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    collect = rb_ary_new2(RARRAY_LEN(ary));
    for (i = 0; i < RARRAY_LEN(ary); i++) {
        rb_ary_push(collect, rb_yield(RARRAY_AREF(ary, i)));
    }
    return collect;
}

Invokes the given block once for each element of self.

Creates a new array containing the values returned by the block.

See also Enumerable#collect.

If no block is given, an Enumerator is returned instead.

a = [ "a", "b", "c", "d" ]
a.collect { |x| x + "!" }        #=> ["a!", "b!", "c!", "d!"]
a.map.with_index{ |x, i| x * i } #=> ["", "b", "cc", "ddd"]
a                                #=> ["a", "b", "c", "d"]
collect! {|item| block } → ary Show source
collect! → Enumerator
static VALUE
rb_ary_collect_bang(VALUE ary)
{
    long i;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    rb_ary_modify(ary);
    for (i = 0; i < RARRAY_LEN(ary); i++) {
        rb_ary_store(ary, i, rb_yield(RARRAY_AREF(ary, i)));
    }
    return ary;
}

Invokes the given block once for each element of self, replacing the element with the value returned by the block.

See also Enumerable#collect.

If no block is given, an Enumerator is returned instead.

a = [ "a", "b", "c", "d" ]
a.map! {|x| x + "!" }
a #=>  [ "a!", "b!", "c!", "d!" ]
a.collect!.with_index {|x, i| x[0...i] }
a #=>  ["", "b", "c!", "d!"]
combination(n) { |c| block } → ary Show source
combination(n) → Enumerator
static VALUE
rb_ary_combination(VALUE ary, VALUE num)
{
    long i, n, len;

    n = NUM2LONG(num);
    RETURN_SIZED_ENUMERATOR(ary, 1, &num, rb_ary_combination_size);
    len = RARRAY_LEN(ary);
    if (n < 0 || len < n) {
        /* yield nothing */
    }
    else if (n == 0) {
        rb_yield(rb_ary_new2(0));
    }
    else if (n == 1) {
        for (i = 0; i < RARRAY_LEN(ary); i++) {
            rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
        }
    }
    else {
        VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
        volatile VALUE t0;
        long *stack = ALLOCV_N(long, t0, n+1);

        RBASIC_CLEAR_CLASS(ary0);
        combinate0(len, n, stack, ary0);
        ALLOCV_END(t0);
        RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
    }
    return ary;
}

When invoked with a block, yields all combinations of length n of elements from the array and then returns the array itself.

The implementation makes no guarantees about the order in which the combinations are yielded.

If no block is given, an Enumerator is returned instead.

Examples:

a = [1, 2, 3, 4]
a.combination(1).to_a  #=> [[1],[2],[3],[4]]
a.combination(2).to_a  #=> [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]
a.combination(3).to_a  #=> [[1,2,3],[1,2,4],[1,3,4],[2,3,4]]
a.combination(4).to_a  #=> [[1,2,3,4]]
a.combination(0).to_a  #=> [[]] # one combination of length 0
a.combination(5).to_a  #=> []   # no combinations of length 5
compact → new_ary Show source
static VALUE
rb_ary_compact(VALUE ary)
{
    ary = rb_ary_dup(ary);
    rb_ary_compact_bang(ary);
    return ary;
}

Returns a copy of self with all nil elements removed.

[ "a", nil, "b", nil, "c", nil ].compact
                  #=> [ "a", "b", "c" ]
compact! → ary or nil Show source
static VALUE
rb_ary_compact_bang(VALUE ary)
{
    VALUE *p, *t, *end;
    long n;

    rb_ary_modify(ary);
    p = t = (VALUE *)RARRAY_CONST_PTR(ary); /* WB: no new reference */
    end = p + RARRAY_LEN(ary);

    while (t < end) {
        if (NIL_P(*t)) t++;
        else *p++ = *t++;
    }
    n = p - RARRAY_CONST_PTR(ary);
    if (RARRAY_LEN(ary) == n) {
        return Qnil;
    }
    ary_resize_smaller(ary, n);

    return ary;
}

Removes nil elements from the array.

Returns nil if no changes were made, otherwise returns the array.

[ "a", nil, "b", nil, "c" ].compact! #=> [ "a", "b", "c" ]
[ "a", "b", "c" ].compact!           #=> nil
concat(other_ary) → ary Show source
VALUE
rb_ary_concat(VALUE x, VALUE y)
{
    rb_ary_modify_check(x);
    y = to_ary(y);
    if (RARRAY_LEN(y) > 0) {
        rb_ary_splice(x, RARRAY_LEN(x), 0, y);
    }
    return x;
}

Appends the elements of other_ary to self.

[ "a", "b" ].concat( ["c", "d"] ) #=> [ "a", "b", "c", "d" ]
a = [ 1, 2, 3 ]
a.concat( [ 4, 5 ] )
a                                 #=> [ 1, 2, 3, 4, 5 ]

See also Array#+.

count → int Show source
count(obj) → int
count { |item| block } → int
static VALUE
rb_ary_count(int argc, VALUE *argv, VALUE ary)
{
    long i, n = 0;

    if (argc == 0) {
        VALUE v;

        if (!rb_block_given_p())
            return LONG2NUM(RARRAY_LEN(ary));

        for (i = 0; i < RARRAY_LEN(ary); i++) {
            v = RARRAY_AREF(ary, i);
            if (RTEST(rb_yield(v))) n++;
        }
    }
    else {
        VALUE obj;

        rb_scan_args(argc, argv, "1", &obj);
        if (rb_block_given_p()) {
            rb_warn("given block not used");
        }
        for (i = 0; i < RARRAY_LEN(ary); i++) {
            if (rb_equal(RARRAY_AREF(ary, i), obj)) n++;
        }
    }

    return LONG2NUM(n);
}

Returns the number of elements.

If an argument is given, counts the number of elements which equal obj using ==.

If a block is given, counts the number of elements for which the block returns a true value.

ary = [1, 2, 4, 2]
ary.count                  #=> 4
ary.count(2)               #=> 2
ary.count { |x| x%2 == 0 } #=> 3
cycle(n=nil) { |obj| block } → nil Show source
cycle(n=nil) → Enumerator
static VALUE
rb_ary_cycle(int argc, VALUE *argv, VALUE ary)
{
    long n, i;
    VALUE nv = Qnil;

    rb_scan_args(argc, argv, "01", &nv);

    RETURN_SIZED_ENUMERATOR(ary, argc, argv, rb_ary_cycle_size);
    if (NIL_P(nv)) {
        n = -1;
    }
    else {
        n = NUM2LONG(nv);
        if (n <= 0) return Qnil;
    }

    while (RARRAY_LEN(ary) > 0 && (n < 0 || 0 < n--)) {
        for (i=0; i<RARRAY_LEN(ary); i++) {
            rb_yield(RARRAY_AREF(ary, i));
        }
    }
    return Qnil;
}

Calls the given block for each element n times or forever if nil is given.

Does nothing if a non-positive number is given or the array is empty.

Returns nil if the loop has finished without getting interrupted.

If no block is given, an Enumerator is returned instead.

a = ["a", "b", "c"]
a.cycle { |x| puts x }     # print, a, b, c, a, b, c,.. forever.
a.cycle(2) { |x| puts x }  # print, a, b, c, a, b, c.
dclone() Show source
# File lib/rexml/xpath_parser.rb, line 32
def dclone
  klone = self.clone
  klone.clear
  self.each{|v| klone << v.dclone}
  klone
end

provides a unified clone operation, for REXML::XPathParser to use across multiple Object+ types

delete(obj) → item or nil Show source
delete(obj) { block } → item or result of block
VALUE
rb_ary_delete(VALUE ary, VALUE item)
{
    VALUE v = item;
    long i1, i2;

    for (i1 = i2 = 0; i1 < RARRAY_LEN(ary); i1++) {
        VALUE e = RARRAY_AREF(ary, i1);

        if (rb_equal(e, item)) {
            v = e;
            continue;
        }
        if (i1 != i2) {
            rb_ary_store(ary, i2, e);
        }
        i2++;
    }
    if (RARRAY_LEN(ary) == i2) {
        if (rb_block_given_p()) {
            return rb_yield(item);
        }
        return Qnil;
    }

    ary_resize_smaller(ary, i2);

    return v;
}

Deletes all items from self that are equal to obj.

Returns the last deleted item, or nil if no matching item is found.

If the optional code block is given, the result of the block is returned if the item is not found. (To remove nil elements and get an informative return value, use #compact!)

a = [ "a", "b", "b", "b", "c" ]
a.delete("b")                   #=> "b"
a                               #=> ["a", "c"]
a.delete("z")                   #=> nil
a.delete("z") { "not found" }   #=> "not found"
delete_at(index) → obj or nil Show source
static VALUE
rb_ary_delete_at_m(VALUE ary, VALUE pos)
{
    return rb_ary_delete_at(ary, NUM2LONG(pos));
}

Deletes the element at the specified index, returning that element, or nil if the index is out of range.

See also #slice!

a = ["ant", "bat", "cat", "dog"]
a.delete_at(2)    #=> "cat"
a                 #=> ["ant", "bat", "dog"]
a.delete_at(99)   #=> nil
delete_if { |item| block } → ary Show source
delete_if → Enumerator
static VALUE
rb_ary_delete_if(VALUE ary)
{
    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    ary_reject_bang(ary);
    return ary;
}

Deletes every element of self for which block evaluates to true.

The array is changed instantly every time the block is called, not after the iteration is over.

See also #reject!

If no block is given, an Enumerator is returned instead.

scores = [ 97, 42, 75 ]
scores.delete_if {|score| score < 80 }   #=> [97]
drop(n) → new_ary Show source
static VALUE
rb_ary_drop(VALUE ary, VALUE n)
{
    VALUE result;
    long pos = NUM2LONG(n);
    if (pos < 0) {
        rb_raise(rb_eArgError, "attempt to drop negative size");
    }

    result = rb_ary_subseq(ary, pos, RARRAY_LEN(ary));
    if (result == Qnil) result = rb_ary_new();
    return result;
}

Drops first n elements from ary and returns the rest of the elements in an array.

If a negative number is given, raises an ArgumentError.

See also #take

a = [1, 2, 3, 4, 5, 0]
a.drop(3)             #=> [4, 5, 0]
drop_while { |arr| block } → new_ary Show source
drop_while → Enumerator
static VALUE
rb_ary_drop_while(VALUE ary)
{
    long i;

    RETURN_ENUMERATOR(ary, 0, 0);
    for (i = 0; i < RARRAY_LEN(ary); i++) {
        if (!RTEST(rb_yield(RARRAY_AREF(ary, i)))) break;
    }
    return rb_ary_drop(ary, LONG2FIX(i));
}

Drops elements up to, but not including, the first element for which the block returns nil or false and returns an array containing the remaining elements.

If no block is given, an Enumerator is returned instead.

See also #take_while

a = [1, 2, 3, 4, 5, 0]
a.drop_while {|i| i < 3 }   #=> [3, 4, 5, 0]
each { |item| block } → ary Show source
each → Enumerator
VALUE
rb_ary_each(VALUE array)
{
    long i;
    volatile VALUE ary = array;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    for (i=0; i<RARRAY_LEN(ary); i++) {
        rb_yield(RARRAY_AREF(ary, i));
    }
    return ary;
}

Calls the given block once for each element in self, passing that element as a parameter.

An Enumerator is returned if no block is given.

a = [ "a", "b", "c" ]
a.each {|x| print x, " -- " }

produces:

a -- b -- c --
each_index { |index| block } → ary Show source
each_index → Enumerator
static VALUE
rb_ary_each_index(VALUE ary)
{
    long i;
    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);

    for (i=0; i<RARRAY_LEN(ary); i++) {
        rb_yield(LONG2NUM(i));
    }
    return ary;
}

Same as #each, but passes the index of the element instead of the element itself.

An Enumerator is returned if no block is given.

a = [ "a", "b", "c" ]
a.each_index {|x| print x, " -- " }

produces:

0 -- 1 -- 2 --
empty? → true or false Show source
static VALUE
rb_ary_empty_p(VALUE ary)
{
    if (RARRAY_LEN(ary) == 0)
        return Qtrue;
    return Qfalse;
}

Returns true if self contains no elements.

[].empty?   #=> true
eql?(other) → true or false Show source
static VALUE
rb_ary_eql(VALUE ary1, VALUE ary2)
{
    if (ary1 == ary2) return Qtrue;
    if (!RB_TYPE_P(ary2, T_ARRAY)) return Qfalse;
    if (RARRAY_LEN(ary1) != RARRAY_LEN(ary2)) return Qfalse;
    if (RARRAY_CONST_PTR(ary1) == RARRAY_CONST_PTR(ary2)) return Qtrue;
    return rb_exec_recursive_paired(recursive_eql, ary1, ary2, ary2);
}

Returns true if self and other are the same object, or are both arrays with the same content (according to Object#eql?).

fetch(index) → obj Show source
fetch(index, default) → obj
fetch(index) { |index| block } → obj
static VALUE
rb_ary_fetch(int argc, VALUE *argv, VALUE ary)
{
    VALUE pos, ifnone;
    long block_given;
    long idx;

    rb_scan_args(argc, argv, "11", &pos, &ifnone);
    block_given = rb_block_given_p();
    if (block_given && argc == 2) {
        rb_warn("block supersedes default value argument");
    }
    idx = NUM2LONG(pos);

    if (idx < 0) {
        idx +=  RARRAY_LEN(ary);
    }
    if (idx < 0 || RARRAY_LEN(ary) <= idx) {
        if (block_given) return rb_yield(pos);
        if (argc == 1) {
            rb_raise(rb_eIndexError, "index %ld outside of array bounds: %ld...%ld",
                        idx - (idx < 0 ? RARRAY_LEN(ary) : 0), -RARRAY_LEN(ary), RARRAY_LEN(ary));
        }
        return ifnone;
    }
    return RARRAY_AREF(ary, idx);
}

Tries to return the element at position index, but throws an IndexError exception if the referenced index lies outside of the array bounds. This error can be prevented by supplying a second argument, which will act as a default value.

Alternatively, if a block is given it will only be executed when an invalid index is referenced. Negative values of index count from the end of the array.

a = [ 11, 22, 33, 44 ]
a.fetch(1)               #=> 22
a.fetch(-1)              #=> 44
a.fetch(4, 'cat')        #=> "cat"
a.fetch(100) { |i| puts "#{i} is out of bounds" }
                         #=> "100 is out of bounds"
fill(obj) → ary Show source
fill(obj, start [, length]) → ary
fill(obj, range ) → ary
fill { |index| block } → ary
fill(start [, length] ) { |index| block } → ary
fill(range) { |index| block } → ary
static VALUE
rb_ary_fill(int argc, VALUE *argv, VALUE ary)
{
    VALUE item, arg1, arg2;
    long beg = 0, end = 0, len = 0;
    int block_p = FALSE;

    if (rb_block_given_p()) {
        block_p = TRUE;
        rb_scan_args(argc, argv, "02", &arg1, &arg2);
        argc += 1;             /* hackish */
    }
    else {
        rb_scan_args(argc, argv, "12", &item, &arg1, &arg2);
    }
    switch (argc) {
      case 1:
        beg = 0;
        len = RARRAY_LEN(ary);
        break;
      case 2:
        if (rb_range_beg_len(arg1, &beg, &len, RARRAY_LEN(ary), 1)) {
            break;
        }
        /* fall through */
      case 3:
        beg = NIL_P(arg1) ? 0 : NUM2LONG(arg1);
        if (beg < 0) {
            beg = RARRAY_LEN(ary) + beg;
            if (beg < 0) beg = 0;
        }
        len = NIL_P(arg2) ? RARRAY_LEN(ary) - beg : NUM2LONG(arg2);
        break;
    }
    rb_ary_modify(ary);
    if (len < 0) {
        return ary;
    }
    if (beg >= ARY_MAX_SIZE || len > ARY_MAX_SIZE - beg) {
        rb_raise(rb_eArgError, "argument too big");
    }
    end = beg + len;
    if (RARRAY_LEN(ary) < end) {
        if (end >= ARY_CAPA(ary)) {
            ary_resize_capa(ary, end);
        }
        ary_mem_clear(ary, RARRAY_LEN(ary), end - RARRAY_LEN(ary));
        ARY_SET_LEN(ary, end);
    }

    if (block_p) {
        VALUE v;
        long i;

        for (i=beg; i<end; i++) {
            v = rb_yield(LONG2NUM(i));
            if (i>=RARRAY_LEN(ary)) break;
            ARY_SET(ary, i, v);
        }
    }
    else {
        ary_memfill(ary, beg, len, item);
    }
    return ary;
}

The first three forms set the selected elements of self (which may be the entire array) to obj.

A start of nil is equivalent to zero.

A length of nil is equivalent to the length of the array.

The last three forms fill the array with the value of the given block, which is passed the absolute index of each element to be filled.

Negative values of start count from the end of the array, where -1 is the last element.

a = [ "a", "b", "c", "d" ]
a.fill("x")              #=> ["x", "x", "x", "x"]
a.fill("z", 2, 2)        #=> ["x", "x", "z", "z"]
a.fill("y", 0..1)        #=> ["y", "y", "z", "z"]
a.fill { |i| i*i }       #=> [0, 1, 4, 9]
a.fill(-2) { |i| i*i*i } #=> [0, 1, 8, 27]
find_index(obj) → int or nil Show source
find_index { |item| block } → int or nil
find_index → Enumerator
static VALUE
rb_ary_index(int argc, VALUE *argv, VALUE ary)
{
    const VALUE *ptr;
    VALUE val;
    long i, len;

    if (argc == 0) {
        RETURN_ENUMERATOR(ary, 0, 0);
        for (i=0; i<RARRAY_LEN(ary); i++) {
            if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) {
                return LONG2NUM(i);
            }
        }
        return Qnil;
    }
    rb_check_arity(argc, 0, 1);
    val = argv[0];
    if (rb_block_given_p())
        rb_warn("given block not used");
    len = RARRAY_LEN(ary);
    ptr = RARRAY_CONST_PTR(ary);
    for (i=0; i<len; i++) {
        VALUE e = ptr[i];
        switch (rb_equal_opt(e, val)) {
          case Qundef:
            if (!rb_equal(e, val)) break;
          case Qtrue:
            return LONG2NUM(i);
          case Qfalse:
            continue;
        }
        len = RARRAY_LEN(ary);
        ptr = RARRAY_CONST_PTR(ary);
    }
    return Qnil;
}

Returns the index of the first object in ary such that the object is == to obj.

If a block is given instead of an argument, returns the index of the first object for which the block returns true. Returns nil if no match is found.

See also #rindex.

An Enumerator is returned if neither a block nor argument is given.

a = [ "a", "b", "c" ]
a.index("b")              #=> 1
a.index("z")              #=> nil
a.index { |x| x == "b" }  #=> 1
first → obj or nil Show source
first(n) → new_ary
static VALUE
rb_ary_first(int argc, VALUE *argv, VALUE ary)
{
    if (argc == 0) {
        if (RARRAY_LEN(ary) == 0) return Qnil;
        return RARRAY_AREF(ary, 0);
    }
    else {
        return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST);
    }
}

Returns the first element, or the first n elements, of the array. If the array is empty, the first form returns nil, and the second form returns an empty array. See also #last for the opposite effect.

a = [ "q", "r", "s", "t" ]
a.first     #=> "q"
a.first(2)  #=> ["q", "r"]
flatten → new_ary Show source
flatten(level) → new_ary
static VALUE
rb_ary_flatten(int argc, VALUE *argv, VALUE ary)
{
    int mod = 0, level = -1;
    VALUE result, lv;

    rb_scan_args(argc, argv, "01", &lv);
    if (!NIL_P(lv)) level = NUM2INT(lv);
    if (level == 0) return ary_make_shared_copy(ary);

    result = flatten(ary, level, &mod);
    OBJ_INFECT(result, ary);

    return result;
}

Returns a new array that is a one-dimensional flattening of self (recursively).

That is, for every element that is an array, extract its elements into the new array.

The optional level argument determines the level of recursion to flatten.

s = [ 1, 2, 3 ]           #=> [1, 2, 3]
t = [ 4, 5, 6, [7, 8] ]   #=> [4, 5, 6, [7, 8]]
a = [ s, t, 9, 10 ]       #=> [[1, 2, 3], [4, 5, 6, [7, 8]], 9, 10]
a.flatten                 #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
a = [ 1, 2, [3, [4, 5] ] ]
a.flatten(1)              #=> [1, 2, 3, [4, 5]]
flatten! → ary or nil Show source
flatten!(level) → ary or nil
static VALUE
rb_ary_flatten_bang(int argc, VALUE *argv, VALUE ary)
{
    int mod = 0, level = -1;
    VALUE result, lv;

    rb_scan_args(argc, argv, "01", &lv);
    rb_ary_modify_check(ary);
    if (!NIL_P(lv)) level = NUM2INT(lv);
    if (level == 0) return Qnil;

    result = flatten(ary, level, &mod);
    if (mod == 0) {
        ary_discard(result);
        return Qnil;
    }
    if (!(mod = ARY_EMBED_P(result))) rb_obj_freeze(result);
    rb_ary_replace(ary, result);
    if (mod) ARY_SET_EMBED_LEN(result, 0);

    return ary;
}

Flattens self in place.

Returns nil if no modifications were made (i.e., the array contains no subarrays.)

The optional level argument determines the level of recursion to flatten.

a = [ 1, 2, [3, [4, 5] ] ]
a.flatten!   #=> [1, 2, 3, 4, 5]
a.flatten!   #=> nil
a            #=> [1, 2, 3, 4, 5]
a = [ 1, 2, [3, [4, 5] ] ]
a.flatten!(1) #=> [1, 2, 3, [4, 5]]
frozen? → true or false Show source
static VALUE
rb_ary_frozen_p(VALUE ary)
{
    if (OBJ_FROZEN(ary)) return Qtrue;
    return Qfalse;
}

Return true if this array is frozen (or temporarily frozen while being sorted). See also Object#frozen?

hash → fixnum Show source
static VALUE
rb_ary_hash(VALUE ary)
{
    long i;
    st_index_t h;
    VALUE n;

    h = rb_hash_start(RARRAY_LEN(ary));
    h = rb_hash_uint(h, (st_index_t)rb_ary_hash);
    for (i=0; i<RARRAY_LEN(ary); i++) {
        n = rb_hash(RARRAY_AREF(ary, i));
        h = rb_hash_uint(h, NUM2LONG(n));
    }
    h = rb_hash_end(h);
    return LONG2FIX(h);
}

Compute a hash-code for this array.

Two arrays with the same content will have the same hash code (and will compare using eql?).

See also Object#hash.

include?(object) → true or false Show source
VALUE
rb_ary_includes(VALUE ary, VALUE item)
{
    long i;
    VALUE e;

    for (i=0; i<RARRAY_LEN(ary); i++) {
        e = RARRAY_AREF(ary, i);
        switch (rb_equal_opt(e, item)) {
          case Qundef:
            if (rb_equal(e, item)) return Qtrue;
            break;
          case Qtrue:
            return Qtrue;
        }
    }
    return Qfalse;
}

Returns true if the given object is present in self (that is, if any element == object), otherwise returns false.

a = [ "a", "b", "c" ]
a.include?("b")   #=> true
a.include?("z")   #=> false
index(obj) → int or nil Show source
index { |item| block } → int or nil
index → Enumerator
static VALUE
rb_ary_index(int argc, VALUE *argv, VALUE ary)
{
    const VALUE *ptr;
    VALUE val;
    long i, len;

    if (argc == 0) {
        RETURN_ENUMERATOR(ary, 0, 0);
        for (i=0; i<RARRAY_LEN(ary); i++) {
            if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) {
                return LONG2NUM(i);
            }
        }
        return Qnil;
    }
    rb_check_arity(argc, 0, 1);
    val = argv[0];
    if (rb_block_given_p())
        rb_warn("given block not used");
    len = RARRAY_LEN(ary);
    ptr = RARRAY_CONST_PTR(ary);
    for (i=0; i<len; i++) {
        VALUE e = ptr[i];
        switch (rb_equal_opt(e, val)) {
          case Qundef:
            if (!rb_equal(e, val)) break;
          case Qtrue:
            return LONG2NUM(i);
          case Qfalse:
            continue;
        }
        len = RARRAY_LEN(ary);
        ptr = RARRAY_CONST_PTR(ary);
    }
    return Qnil;
}

Returns the index of the first object in ary such that the object is == to obj.

If a block is given instead of an argument, returns the index of the first object for which the block returns true. Returns nil if no match is found.

See also #rindex.

An Enumerator is returned if neither a block nor argument is given.

a = [ "a", "b", "c" ]
a.index("b")              #=> 1
a.index("z")              #=> nil
a.index { |x| x == "b" }  #=> 1
initialize_copy(other_ary) → ary Show source
VALUE
rb_ary_replace(VALUE copy, VALUE orig)
{
    rb_ary_modify_check(copy);
    orig = to_ary(orig);
    if (copy == orig) return copy;

    if (RARRAY_LEN(orig) <= RARRAY_EMBED_LEN_MAX) {
        VALUE shared = 0;

        if (ARY_OWNS_HEAP_P(copy)) {
            RARRAY_PTR_USE(copy, ptr, ruby_sized_xfree(ptr, ARY_HEAP_SIZE(copy)));
        }
        else if (ARY_SHARED_P(copy)) {
            shared = ARY_SHARED(copy);
            FL_UNSET_SHARED(copy);
        }
        FL_SET_EMBED(copy);
        ary_memcpy(copy, 0, RARRAY_LEN(orig), RARRAY_CONST_PTR(orig));
        if (shared) {
            rb_ary_decrement_share(shared);
        }
        ARY_SET_LEN(copy, RARRAY_LEN(orig));
    }
    else {
        VALUE shared = ary_make_shared(orig);
        if (ARY_OWNS_HEAP_P(copy)) {
            RARRAY_PTR_USE(copy, ptr, ruby_sized_xfree(ptr, ARY_HEAP_SIZE(copy)));
        }
        else {
            rb_ary_unshare_safe(copy);
        }
        FL_UNSET_EMBED(copy);
        ARY_SET_PTR(copy, RARRAY_CONST_PTR(orig));
        ARY_SET_LEN(copy, RARRAY_LEN(orig));
        rb_ary_set_shared(copy, shared);
    }
    return copy;
}

Replaces the contents of self with the contents of other_ary, truncating or expanding if necessary.

a = [ "a", "b", "c", "d", "e" ]
a.replace([ "x", "y", "z" ])   #=> ["x", "y", "z"]
a                              #=> ["x", "y", "z"]
insert(index, obj...) → ary Show source
static VALUE
rb_ary_insert(int argc, VALUE *argv, VALUE ary)
{
    long pos;

    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    rb_ary_modify_check(ary);
    if (argc == 1) return ary;
    pos = NUM2LONG(argv[0]);
    if (pos == -1) {
        pos = RARRAY_LEN(ary);
    }
    if (pos < 0) {
        pos++;
    }
    rb_ary_splice(ary, pos, 0, rb_ary_new4(argc - 1, argv + 1));
    return ary;
}

Inserts the given values before the element with the given index.

Negative indices count backwards from the end of the array, where -1 is the last element. If a negative index is used, the given values will be inserted after that element, so using an index of -1 will insert the values at the end of the array.

a = %w{ a b c d }
a.insert(2, 99)         #=> ["a", "b", 99, "c", "d"]
a.insert(-2, 1, 2, 3)   #=> ["a", "b", 99, "c", 1, 2, 3, "d"]
inspect → string Show source
to_s → string
static VALUE
rb_ary_inspect(VALUE ary)
{
    if (RARRAY_LEN(ary) == 0) return rb_usascii_str_new2("[]");
    return rb_exec_recursive(inspect_ary, ary, 0);
}

Creates a string representation of self.

[ "a", "b", "c" ].to_s     #=> "[\"a\", \"b\", \"c\"]"
Also aliased as: to_s
join(separator=$,) → str Show source
static VALUE
rb_ary_join_m(int argc, VALUE *argv, VALUE ary)
{
    VALUE sep;

    rb_scan_args(argc, argv, "01", &sep);
    if (NIL_P(sep)) sep = rb_output_fs;

    return rb_ary_join(ary, sep);
}

Returns a string created by converting each element of the array to a string, separated by the given separator. If the separator is nil, it uses current $,. If both the separator and $, are nil, it uses empty string.

[ "a", "b", "c" ].join        #=> "abc"
[ "a", "b", "c" ].join("-")   #=> "a-b-c"
keep_if { |item| block } → ary Show source
keep_if → Enumerator
static VALUE
rb_ary_keep_if(VALUE ary)
{
    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    rb_ary_select_bang(ary);
    return ary;
}

Deletes every element of self for which the given block evaluates to false.

See also #select!

If no block is given, an Enumerator is returned instead.

a = %w{ a b c d e f }
a.keep_if { |v| v =~ /[aeiou]/ }  #=> ["a", "e"]
last → obj or nil Show source
last(n) → new_ary
VALUE
rb_ary_last(int argc, const VALUE *argv, VALUE ary)
{
    if (argc == 0) {
        long len = RARRAY_LEN(ary);
        if (len == 0) return Qnil;
        return RARRAY_AREF(ary, len-1);
    }
    else {
        return ary_take_first_or_last(argc, argv, ary, ARY_TAKE_LAST);
    }
}

Returns the last element(s) of self. If the array is empty, the first form returns nil.

See also #first for the opposite effect.

a = [ "w", "x", "y", "z" ]
a.last     #=> "z"
a.last(2)  #=> ["y", "z"]
length → int Show source
static VALUE
rb_ary_length(VALUE ary)
{
    long len = RARRAY_LEN(ary);
    return LONG2NUM(len);
}

Returns the number of elements in self. May be zero.

[ 1, 2, 3, 4, 5 ].length   #=> 5
[].length                  #=> 0
Also aliased as: size
map { |item| block } → new_ary Show source
map → Enumerator
static VALUE
rb_ary_collect(VALUE ary)
{
    long i;
    VALUE collect;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    collect = rb_ary_new2(RARRAY_LEN(ary));
    for (i = 0; i < RARRAY_LEN(ary); i++) {
        rb_ary_push(collect, rb_yield(RARRAY_AREF(ary, i)));
    }
    return collect;
}

Invokes the given block once for each element of self.

Creates a new array containing the values returned by the block.

See also Enumerable#collect.

If no block is given, an Enumerator is returned instead.

a = [ "a", "b", "c", "d" ]
a.collect { |x| x + "!" }        #=> ["a!", "b!", "c!", "d!"]
a.map.with_index{ |x, i| x * i } #=> ["", "b", "cc", "ddd"]
a                                #=> ["a", "b", "c", "d"]
map! {|item| block } → ary Show source
map! → Enumerator
static VALUE
rb_ary_collect_bang(VALUE ary)
{
    long i;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    rb_ary_modify(ary);
    for (i = 0; i < RARRAY_LEN(ary); i++) {
        rb_ary_store(ary, i, rb_yield(RARRAY_AREF(ary, i)));
    }
    return ary;
}

Invokes the given block once for each element of self, replacing the element with the value returned by the block.

See also Enumerable#collect.

If no block is given, an Enumerator is returned instead.

a = [ "a", "b", "c", "d" ]
a.map! {|x| x + "!" }
a #=>  [ "a!", "b!", "c!", "d!" ]
a.collect!.with_index {|x, i| x[0...i] }
a #=>  ["", "b", "c!", "d!"]
pack ( aTemplateString ) → aBinaryString Show source
static VALUE
pack_pack(VALUE ary, VALUE fmt)
{
    static const char nul10[] = "\0\0\0\0\0\0\0\0\0\0";
    static const char spc10[] = "          ";
    const char *p, *pend;
    VALUE res, from, associates = 0;
    char type;
    long items, len, idx, plen;
    const char *ptr;
    int enc_info = 1;           /* 0 - BINARY, 1 - US-ASCII, 2 - UTF-8 */
#ifdef NATINT_PACK
    int natint;         /* native integer */
#endif
    int integer_size, bigendian_p;

    StringValue(fmt);
    p = RSTRING_PTR(fmt);
    pend = p + RSTRING_LEN(fmt);
    res = rb_str_buf_new(0);

    items = RARRAY_LEN(ary);
    idx = 0;

#define TOO_FEW (rb_raise(rb_eArgError, toofew), 0)
#define THISFROM (items > 0 ? RARRAY_AREF(ary, idx) : TOO_FEW)
#define NEXTFROM (items-- > 0 ? RARRAY_AREF(ary, idx++) : TOO_FEW)

    while (p < pend) {
        int explicit_endian = 0;
        if (RSTRING_PTR(fmt) + RSTRING_LEN(fmt) != pend) {
            rb_raise(rb_eRuntimeError, "format string modified");
        }
        type = *p++;           /* get data type */
#ifdef NATINT_PACK
        natint = 0;
#endif

        if (ISSPACE(type)) continue;
        if (type == '#') {
            while ((p < pend) && (*p != '\n')) {
                p++;
            }
            continue;
        }

        {
          modifiers:
            switch (*p) {
              case '_':
              case '!':
                if (strchr(natstr, type)) {
#ifdef NATINT_PACK
                    natint = 1;
#endif
                    p++;
                }
                else {
                    rb_raise(rb_eArgError, "'%c' allowed only after types %s", *p, natstr);
                }
                goto modifiers;

              case '<':
              case '>':
                if (!strchr(endstr, type)) {
                    rb_raise(rb_eArgError, "'%c' allowed only after types %s", *p, endstr);
                }
                if (explicit_endian) {
                    rb_raise(rb_eRangeError, "Can't use both '<' and '>'");
                }
                explicit_endian = *p++;
                goto modifiers;
            }
        }

        if (*p == '*') {       /* set data length */
            len = strchr("@Xxu", type) ? 0
                : strchr("PMm", type) ? 1
                : items;
            p++;
        }
        else if (ISDIGIT(*p)) {
            errno = 0;
            len = STRTOUL(p, (char**)&p, 10);
            if (errno) {
                rb_raise(rb_eRangeError, "pack length too big");
            }
        }
        else {
            len = 1;
        }

        switch (type) {
          case 'U':
            /* if encoding is US-ASCII, upgrade to UTF-8 */
            if (enc_info == 1) enc_info = 2;
            break;
          case 'm': case 'M': case 'u':
            /* keep US-ASCII (do nothing) */
            break;
          default:
            /* fall back to BINARY */
            enc_info = 0;
            break;
        }
        switch (type) {
          case 'A': case 'a': case 'Z':
          case 'B': case 'b':
          case 'H': case 'h':
            from = NEXTFROM;
            if (NIL_P(from)) {
                ptr = "";
                plen = 0;
            }
            else {
                StringValue(from);
                ptr = RSTRING_PTR(from);
                plen = RSTRING_LEN(from);
                OBJ_INFECT(res, from);
            }

            if (p[-1] == '*')
                len = plen;

            switch (type) {
              case 'a':                /* arbitrary binary string (null padded)  */
              case 'A':         /* arbitrary binary string (ASCII space padded) */
              case 'Z':         /* null terminated string  */
                if (plen >= len) {
                    rb_str_buf_cat(res, ptr, len);
                    if (p[-1] == '*' && type == 'Z')
                        rb_str_buf_cat(res, nul10, 1);
                }
                else {
                    rb_str_buf_cat(res, ptr, plen);
                    len -= plen;
                    while (len >= 10) {
                        rb_str_buf_cat(res, (type == 'A')?spc10:nul10, 10);
                        len -= 10;
                    }
                    rb_str_buf_cat(res, (type == 'A')?spc10:nul10, len);
                }
                break;

#define castchar(from) (char)((from) & 0xff)

              case 'b':                /* bit string (ascending) */
                {
                    int byte = 0;
                    long i, j = 0;

                    if (len > plen) {
                        j = (len - plen + 1)/2;
                        len = plen;
                    }
                    for (i=0; i++ < len; ptr++) {
                        if (*ptr & 1)
                            byte |= 128;
                        if (i & 7)
                            byte >>= 1;
                        else {
                            char c = castchar(byte);
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 7) {
                        char c;
                        byte >>= 7 - (len & 7);
                        c = castchar(byte);
                        rb_str_buf_cat(res, &c, 1);
                    }
                    len = j;
                    goto grow;
                }
                break;

              case 'B':                /* bit string (descending) */
                {
                    int byte = 0;
                    long i, j = 0;

                    if (len > plen) {
                        j = (len - plen + 1)/2;
                        len = plen;
                    }
                    for (i=0; i++ < len; ptr++) {
                        byte |= *ptr & 1;
                        if (i & 7)
                            byte <<= 1;
                        else {
                            char c = castchar(byte);
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 7) {
                        char c;
                        byte <<= 7 - (len & 7);
                        c = castchar(byte);
                        rb_str_buf_cat(res, &c, 1);
                    }
                    len = j;
                    goto grow;
                }
                break;

              case 'h':                /* hex string (low nibble first) */
                {
                    int byte = 0;
                    long i, j = 0;

                    if (len > plen) {
                        j = (len + 1) / 2 - (plen + 1) / 2;
                        len = plen;
                    }
                    for (i=0; i++ < len; ptr++) {
                        if (ISALPHA(*ptr))
                            byte |= (((*ptr & 15) + 9) & 15) << 4;
                        else
                            byte |= (*ptr & 15) << 4;
                        if (i & 1)
                            byte >>= 4;
                        else {
                            char c = castchar(byte);
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 1) {
                        char c = castchar(byte);
                        rb_str_buf_cat(res, &c, 1);
                    }
                    len = j;
                    goto grow;
                }
                break;

              case 'H':                /* hex string (high nibble first) */
                {
                    int byte = 0;
                    long i, j = 0;

                    if (len > plen) {
                        j = (len + 1) / 2 - (plen + 1) / 2;
                        len = plen;
                    }
                    for (i=0; i++ < len; ptr++) {
                        if (ISALPHA(*ptr))
                            byte |= ((*ptr & 15) + 9) & 15;
                        else
                            byte |= *ptr & 15;
                        if (i & 1)
                            byte <<= 4;
                        else {
                            char c = castchar(byte);
                            rb_str_buf_cat(res, &c, 1);
                            byte = 0;
                        }
                    }
                    if (len & 1) {
                        char c = castchar(byte);
                        rb_str_buf_cat(res, &c, 1);
                    }
                    len = j;
                    goto grow;
                }
                break;
            }
            break;

          case 'c':            /* signed char */
          case 'C':            /* unsigned char */
            integer_size = 1;
            bigendian_p = BIGENDIAN_P(); /* not effective */
            goto pack_integer;

          case 's':            /* s for int16_t, s! for signed short */
            integer_size = NATINT_LEN(short, 2);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'S':            /* S for uint16_t, S! for unsigned short */
            integer_size = NATINT_LEN(short, 2);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'i':            /* i and i! for signed int */
            integer_size = (int)sizeof(int);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'I':            /* I and I! for unsigned int */
            integer_size = (int)sizeof(int);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'l':            /* l for int32_t, l! for signed long */
            integer_size = NATINT_LEN(long, 4);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'L':            /* L for uint32_t, L! for unsigned long */
            integer_size = NATINT_LEN(long, 4);
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'q':            /* q for int64_t, q! for signed long long */
            integer_size = NATINT_LEN_Q;
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'Q':            /* Q for uint64_t, Q! for unsigned long long */
            integer_size = NATINT_LEN_Q;
            bigendian_p = BIGENDIAN_P();
            goto pack_integer;

          case 'n':            /* 16 bit (2 bytes) integer (network byte-order)  */
            integer_size = 2;
            bigendian_p = 1;
            goto pack_integer;

          case 'N':            /* 32 bit (4 bytes) integer (network byte-order) */
            integer_size = 4;
            bigendian_p = 1;
            goto pack_integer;

          case 'v':            /* 16 bit (2 bytes) integer (VAX byte-order) */
            integer_size = 2;
            bigendian_p = 0;
            goto pack_integer;

          case 'V':            /* 32 bit (4 bytes) integer (VAX byte-order) */
            integer_size = 4;
            bigendian_p = 0;
            goto pack_integer;

          pack_integer:
            if (explicit_endian) {
                bigendian_p = explicit_endian == '>';
            }
            if (integer_size > MAX_INTEGER_PACK_SIZE)
                rb_bug("unexpected intger size for pack: %d", integer_size);
            while (len-- > 0) {
                char intbuf[MAX_INTEGER_PACK_SIZE];

                from = NEXTFROM;
                rb_integer_pack(from, intbuf, integer_size, 1, 0,
                    INTEGER_PACK_2COMP |
                    (bigendian_p ? INTEGER_PACK_BIG_ENDIAN : INTEGER_PACK_LITTLE_ENDIAN));
                rb_str_buf_cat(res, intbuf, integer_size);
            }
            break;

          case 'f':            /* single precision float in native format */
          case 'F':            /* ditto */
            while (len-- > 0) {
                float f;

                from = NEXTFROM;
                f = (float)RFLOAT_VALUE(rb_to_float(from));
                rb_str_buf_cat(res, (char*)&f, sizeof(float));
            }
            break;

          case 'e':            /* single precision float in VAX byte-order */
            while (len-- > 0) {
                FLOAT_CONVWITH(tmp);

                from = NEXTFROM;
                tmp.f = (float)RFLOAT_VALUE(rb_to_float(from));
                HTOVF(tmp);
                rb_str_buf_cat(res, tmp.buf, sizeof(float));
            }
            break;

          case 'E':            /* double precision float in VAX byte-order */
            while (len-- > 0) {
                DOUBLE_CONVWITH(tmp);
                from = NEXTFROM;
                tmp.d = RFLOAT_VALUE(rb_to_float(from));
                HTOVD(tmp);
                rb_str_buf_cat(res, tmp.buf, sizeof(double));
            }
            break;

          case 'd':            /* double precision float in native format */
          case 'D':            /* ditto */
            while (len-- > 0) {
                double d;

                from = NEXTFROM;
                d = RFLOAT_VALUE(rb_to_float(from));
                rb_str_buf_cat(res, (char*)&d, sizeof(double));
            }
            break;

          case 'g':            /* single precision float in network byte-order */
            while (len-- > 0) {
                FLOAT_CONVWITH(tmp);
                from = NEXTFROM;
                tmp.f = (float)RFLOAT_VALUE(rb_to_float(from));
                HTONF(tmp);
                rb_str_buf_cat(res, tmp.buf, sizeof(float));
            }
            break;

          case 'G':            /* double precision float in network byte-order */
            while (len-- > 0) {
                DOUBLE_CONVWITH(tmp);

                from = NEXTFROM;
                tmp.d = RFLOAT_VALUE(rb_to_float(from));
                HTOND(tmp);
                rb_str_buf_cat(res, tmp.buf, sizeof(double));
            }
            break;

          case 'x':            /* null byte */
          grow:
            while (len >= 10) {
                rb_str_buf_cat(res, nul10, 10);
                len -= 10;
            }
            rb_str_buf_cat(res, nul10, len);
            break;

          case 'X':            /* back up byte */
          shrink:
            plen = RSTRING_LEN(res);
            if (plen < len)
                rb_raise(rb_eArgError, "X outside of string");
            rb_str_set_len(res, plen - len);
            break;

          case '@':            /* null fill to absolute position */
            len -= RSTRING_LEN(res);
            if (len > 0) goto grow;
            len = -len;
            if (len > 0) goto shrink;
            break;

          case '%':
            rb_raise(rb_eArgError, "%% is not supported");
            break;

          case 'U':            /* Unicode character */
            while (len-- > 0) {
                SIGNED_VALUE l;
                char buf[8];
                int le;

                from = NEXTFROM;
                from = rb_to_int(from);
                l = NUM2LONG(from);
                if (l < 0) {
                    rb_raise(rb_eRangeError, "pack(U): value out of range");
                }
                le = rb_uv_to_utf8(buf, l);
                rb_str_buf_cat(res, (char*)buf, le);
            }
            break;

          case 'u':            /* uuencoded string */
          case 'm':            /* base64 encoded string */
            from = NEXTFROM;
            StringValue(from);
            ptr = RSTRING_PTR(from);
            plen = RSTRING_LEN(from);

            if (len == 0 && type == 'm') {
                encodes(res, ptr, plen, type, 0);
                ptr += plen;
                break;
            }
            if (len <= 2)
                len = 45;
            else if (len > 63 && type == 'u')
                len = 63;
            else
                len = len / 3 * 3;
            while (plen > 0) {
                long todo;

                if (plen > len)
                    todo = len;
                else
                    todo = plen;
                encodes(res, ptr, todo, type, 1);
                plen -= todo;
                ptr += todo;
            }
            break;

          case 'M':            /* quoted-printable encoded string */
            from = rb_obj_as_string(NEXTFROM);
            if (len <= 1)
                len = 72;
            qpencode(res, from, len);
            break;

          case 'P':            /* pointer to packed byte string */
            from = THISFROM;
            if (!NIL_P(from)) {
                StringValue(from);
                if (RSTRING_LEN(from) < len) {
                    rb_raise(rb_eArgError, "too short buffer for P(%ld for %ld)",
                             RSTRING_LEN(from), len);
                }
            }
            len = 1;
            /* FALL THROUGH */
          case 'p':            /* pointer to string */
            while (len-- > 0) {
                char *t;
                from = NEXTFROM;
                if (NIL_P(from)) {
                    t = 0;
                }
                else {
                    t = StringValuePtr(from);
                    rb_obj_taint(from);
                }
                if (!associates) {
                    associates = rb_ary_new();
                }
                rb_ary_push(associates, from);
                rb_str_buf_cat(res, (char*)&t, sizeof(char*));
            }
            break;

          case 'w':            /* BER compressed integer  */
            while (len-- > 0) {
                VALUE buf = rb_str_new(0, 0);
                size_t numbytes;
                int sign;
                char *cp;

                from = NEXTFROM;
                from = rb_to_int(from);
                numbytes = rb_absint_numwords(from, 7, NULL);
                if (numbytes == 0)
                    numbytes = 1;
                buf = rb_str_new(NULL, numbytes);

                sign = rb_integer_pack(from, RSTRING_PTR(buf), RSTRING_LEN(buf), 1, 1, INTEGER_PACK_BIG_ENDIAN);

                if (sign < 0)
                    rb_raise(rb_eArgError, "can't compress negative numbers");
                if (sign == 2)
                    rb_bug("buffer size problem?");

                cp = RSTRING_PTR(buf);
                while (1 < numbytes) {
                  *cp |= 0x80;
                  cp++;
                  numbytes--;
                }

                rb_str_buf_cat(res, RSTRING_PTR(buf), RSTRING_LEN(buf));
            }
            break;

          default: {
            char unknown[5];
            if (ISPRINT(type)) {
                unknown[0] = type;
                unknown[1] = '\0';
            }
            else {
                snprintf(unknown, sizeof(unknown), "\\x%.2x", type & 0xff);
            }
            rb_warning("unknown pack directive '%s' in '% "PRIsVALUE"'",
                       unknown, fmt);
            break;
          }
        }
    }

    if (associates) {
        str_associate(res, associates);
    }
    OBJ_INFECT(res, fmt);
    switch (enc_info) {
      case 1:
        ENCODING_CODERANGE_SET(res, rb_usascii_encindex(), ENC_CODERANGE_7BIT);
        break;
      case 2:
        rb_enc_set_index(res, rb_utf8_encindex());
        break;
      default:
        /* do nothing, keep ASCII-8BIT */
        break;
    }
    return res;
}

Packs the contents of arr into a binary sequence according to the directives in aTemplateString (see the table below) Directives “A,'' “a,'' and “Z'' may be followed by a count, which gives the width of the resulting field. The remaining directives also may take a count, indicating the number of array elements to convert. If the count is an asterisk (“*''), all remaining array elements will be converted. Any of the directives “sSiIlL'' may be followed by an underscore (“_'') or exclamation mark (“!'') to use the underlying platform's native size for the specified type; otherwise, they use a platform-independent size. Spaces are ignored in the template string. See also String#unpack.

a = [ "a", "b", "c" ]
n = [ 65, 66, 67 ]
a.pack("A3A3A3")   #=> "a  b  c  "
a.pack("a3a3a3")   #=> "a\000\000b\000\000c\000\000"
n.pack("ccc")      #=> "ABC"

Directives for pack.

Integer      | Array   |
Directive    | Element | Meaning
---------------------------------------------------------------------------
   C         | Integer | 8-bit unsigned (unsigned char)
   S         | Integer | 16-bit unsigned, native endian (uint16_t)
   L         | Integer | 32-bit unsigned, native endian (uint32_t)
   Q         | Integer | 64-bit unsigned, native endian (uint64_t)
             |         |
   c         | Integer | 8-bit signed (signed char)
   s         | Integer | 16-bit signed, native endian (int16_t)
   l         | Integer | 32-bit signed, native endian (int32_t)
   q         | Integer | 64-bit signed, native endian (int64_t)
             |         |
   S_, S!    | Integer | unsigned short, native endian
   I, I_, I! | Integer | unsigned int, native endian
   L_, L!    | Integer | unsigned long, native endian
   Q_, Q!    | Integer | unsigned long long, native endian (ArgumentError
             |         | if the platform has no long long type.)
             |         | (Q_ and Q! is available since Ruby 2.1.)
             |         |
   s_, s!    | Integer | signed short, native endian
   i, i_, i! | Integer | signed int, native endian
   l_, l!    | Integer | signed long, native endian
   q_, q!    | Integer | signed long long, native endian (ArgumentError
             |         | if the platform has no long long type.)
             |         | (q_ and q! is available since Ruby 2.1.)
             |         |
   S> L> Q>  | Integer | same as the directives without ">" except
   s> l> q>  |         | big endian
   S!> I!>   |         | (available since Ruby 1.9.3)
   L!> Q!>   |         | "S>" is same as "n"
   s!> i!>   |         | "L>" is same as "N"
   l!> q!>   |         |
             |         |
   S< L< Q<  | Integer | same as the directives without "<" except
   s< l< q<  |         | little endian
   S!< I!<   |         | (available since Ruby 1.9.3)
   L!< Q!<   |         | "S<" is same as "v"
   s!< i!<   |         | "L<" is same as "V"
   l!< q!<   |         |
             |         |
   n         | Integer | 16-bit unsigned, network (big-endian) byte order
   N         | Integer | 32-bit unsigned, network (big-endian) byte order
   v         | Integer | 16-bit unsigned, VAX (little-endian) byte order
   V         | Integer | 32-bit unsigned, VAX (little-endian) byte order
             |         |
   U         | Integer | UTF-8 character
   w         | Integer | BER-compressed integer

Float        |         |
Directive    |         | Meaning
---------------------------------------------------------------------------
   D, d      | Float   | double-precision, native format
   F, f      | Float   | single-precision, native format
   E         | Float   | double-precision, little-endian byte order
   e         | Float   | single-precision, little-endian byte order
   G         | Float   | double-precision, network (big-endian) byte order
   g         | Float   | single-precision, network (big-endian) byte order

String       |         |
Directive    |         | Meaning
---------------------------------------------------------------------------
   A         | String  | arbitrary binary string (space padded, count is width)
   a         | String  | arbitrary binary string (null padded, count is width)
   Z         | String  | same as ``a'', except that null is added with *
   B         | String  | bit string (MSB first)
   b         | String  | bit string (LSB first)
   H         | String  | hex string (high nibble first)
   h         | String  | hex string (low nibble first)
   u         | String  | UU-encoded string
   M         | String  | quoted printable, MIME encoding (see RFC2045)
   m         | String  | base64 encoded string (see RFC 2045, count is width)
             |         | (if count is 0, no line feed are added, see RFC 4648)
   P         | String  | pointer to a structure (fixed-length string)
   p         | String  | pointer to a null-terminated string

Misc.        |         |
Directive    |         | Meaning
---------------------------------------------------------------------------
   @         | ---     | moves to absolute position
   X         | ---     | back up a byte
   x         | ---     | null byte
permutation { |p| block } → ary Show source
permutation → Enumerator
permutation(n) { |p| block } → ary
permutation(n) → Enumerator
static VALUE
rb_ary_permutation(int argc, VALUE *argv, VALUE ary)
{
    VALUE num;
    long r, n, i;

    n = RARRAY_LEN(ary);                  /* Array length */
    RETURN_SIZED_ENUMERATOR(ary, argc, argv, rb_ary_permutation_size);   /* Return enumerator if no block */
    rb_scan_args(argc, argv, "01", &num);
    r = NIL_P(num) ? n : NUM2LONG(num);   /* Permutation size from argument */

    if (r < 0 || n < r) {
        /* no permutations: yield nothing */
    }
    else if (r == 0) { /* exactly one permutation: the zero-length array */
        rb_yield(rb_ary_new2(0));
    }
    else if (r == 1) { /* this is a special, easy case */
        for (i = 0; i < RARRAY_LEN(ary); i++) {
            rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
        }
    }
    else {             /* this is the general case */
        volatile VALUE t0;
        long *p = (long*)ALLOCV(t0, r*sizeof(long)+n*sizeof(char));
        char *used = (char*)(p + r);
        VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
        RBASIC_CLEAR_CLASS(ary0);

        MEMZERO(used, char, n); /* initialize array */

        permute0(n, r, p, used, ary0); /* compute and yield permutations */
        ALLOCV_END(t0);
        RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
    }
    return ary;
}

When invoked with a block, yield all permutations of length n of the elements of the array, then return the array itself.

If n is not specified, yield all permutations of all elements.

The implementation makes no guarantees about the order in which the permutations are yielded.

If no block is given, an Enumerator is returned instead.

Examples:

a = [1, 2, 3]
a.permutation.to_a    #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
a.permutation(1).to_a #=> [[1],[2],[3]]
a.permutation(2).to_a #=> [[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]]
a.permutation(3).to_a #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
a.permutation(0).to_a #=> [[]] # one permutation of length 0
a.permutation(4).to_a #=> []   # no permutations of length 4
pop → obj or nil Show source
pop(n) → new_ary
static VALUE
rb_ary_pop_m(int argc, VALUE *argv, VALUE ary)
{
    VALUE result;

    if (argc == 0) {
        return rb_ary_pop(ary);
    }

    rb_ary_modify_check(ary);
    result = ary_take_first_or_last(argc, argv, ary, ARY_TAKE_LAST);
    ARY_INCREASE_LEN(ary, -RARRAY_LEN(result));
    return result;
}

Removes the last element from self and returns it, or nil if the array is empty.

If a number n is given, returns an array of the last n elements (or less) just like array.slice!(-n, n) does. See also #push for the opposite effect.

a = [ "a", "b", "c", "d" ]
a.pop     #=> "d"
a.pop(2)  #=> ["b", "c"]
a         #=> ["a"]
product(other_ary, ...) → new_ary Show source
product(other_ary, ...) { |p| block } → ary
static VALUE
rb_ary_product(int argc, VALUE *argv, VALUE ary)
{
    int n = argc+1;    /* How many arrays we're operating on */
    volatile VALUE t0 = tmpary(n);
    volatile VALUE t1 = tmpbuf(n, sizeof(int));
    VALUE *arrays = RARRAY_PTR(t0); /* The arrays we're computing the product of */
    int *counters = (int*)RSTRING_PTR(t1); /* The current position in each one */
    VALUE result = Qnil;      /* The array we'll be returning, when no block given */
    long i,j;
    long resultlen = 1;

    RBASIC_CLEAR_CLASS(t0);
    RBASIC_CLEAR_CLASS(t1);

    /* initialize the arrays of arrays */
    ARY_SET_LEN(t0, n);
    arrays[0] = ary;
    for (i = 1; i < n; i++) arrays[i] = Qnil;
    for (i = 1; i < n; i++) arrays[i] = to_ary(argv[i-1]);

    /* initialize the counters for the arrays */
    for (i = 0; i < n; i++) counters[i] = 0;

    /* Otherwise, allocate and fill in an array of results */
    if (rb_block_given_p()) {
        /* Make defensive copies of arrays; exit if any is empty */
        for (i = 0; i < n; i++) {
            if (RARRAY_LEN(arrays[i]) == 0) goto done;
            arrays[i] = ary_make_shared_copy(arrays[i]);
        }
    }
    else {
        /* Compute the length of the result array; return [] if any is empty */
        for (i = 0; i < n; i++) {
            long k = RARRAY_LEN(arrays[i]);
            if (k == 0) {
                result = rb_ary_new2(0);
                goto done;
            }
            if (MUL_OVERFLOW_LONG_P(resultlen, k))
                rb_raise(rb_eRangeError, "too big to product");
            resultlen *= k;
        }
        result = rb_ary_new2(resultlen);
    }
    for (;;) {
        int m;
        /* fill in one subarray */
        VALUE subarray = rb_ary_new2(n);
        for (j = 0; j < n; j++) {
            rb_ary_push(subarray, rb_ary_entry(arrays[j], counters[j]));
        }

        /* put it on the result array */
        if (NIL_P(result)) {
            FL_SET(t0, FL_USER5);
            rb_yield(subarray);
            if (! FL_TEST(t0, FL_USER5)) {
                rb_raise(rb_eRuntimeError, "product reentered");
            }
            else {
                FL_UNSET(t0, FL_USER5);
            }
        }
        else {
            rb_ary_push(result, subarray);
        }

        /*
         * Increment the last counter.  If it overflows, reset to 0
         * and increment the one before it.
         */
        m = n-1;
        counters[m]++;
        while (counters[m] == RARRAY_LEN(arrays[m])) {
            counters[m] = 0;
            /* If the first counter overflows, we are done */
            if (--m < 0) goto done;
            counters[m]++;
        }
    }
done:
    tmpary_discard(t0);
    tmpbuf_discard(t1);

    return NIL_P(result) ? ary : result;
}

Returns an array of all combinations of elements from all arrays.

The length of the returned array is the product of the length of self and the argument arrays.

If given a block, product will yield all combinations and return self instead.

[1,2,3].product([4,5])     #=> [[1,4],[1,5],[2,4],[2,5],[3,4],[3,5]]
[1,2].product([1,2])       #=> [[1,1],[1,2],[2,1],[2,2]]
[1,2].product([3,4],[5,6]) #=> [[1,3,5],[1,3,6],[1,4,5],[1,4,6],
                           #     [2,3,5],[2,3,6],[2,4,5],[2,4,6]]
[1,2].product()            #=> [[1],[2]]
[1,2].product([])          #=> []
push(obj, ... ) → ary Show source
static VALUE
rb_ary_push_m(int argc, VALUE *argv, VALUE ary)
{
    return rb_ary_cat(ary, argv, argc);
}

Append — Pushes the given object(s) on to the end of this array. This expression returns the array itself, so several appends may be chained together. See also #pop for the opposite effect.

a = [ "a", "b", "c" ]
a.push("d", "e", "f")
        #=> ["a", "b", "c", "d", "e", "f"]
[1, 2, 3,].push(4).push(5)
        #=> [1, 2, 3, 4, 5]
rassoc(obj) → new_ary or nil Show source
VALUE
rb_ary_rassoc(VALUE ary, VALUE value)
{
    long i;
    VALUE v;

    for (i = 0; i < RARRAY_LEN(ary); ++i) {
        v = RARRAY_AREF(ary, i);
        if (RB_TYPE_P(v, T_ARRAY) &&
            RARRAY_LEN(v) > 1 &&
            rb_equal(RARRAY_AREF(v, 1), value))
            return v;
    }
    return Qnil;
}

Searches through the array whose elements are also arrays.

Compares obj with the second element of each contained array using obj.==.

Returns the first contained array that matches obj.

See also #assoc.

a = [ [ 1, "one"], [2, "two"], [3, "three"], ["ii", "two"] ]
a.rassoc("two")    #=> [2, "two"]
a.rassoc("four")   #=> nil
reject {|item| block } → new_ary Show source
reject → Enumerator
static VALUE
rb_ary_reject(VALUE ary)
{
    VALUE rejected_ary;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    rejected_ary = rb_ary_new();
    ary_reject(ary, rejected_ary);
    return rejected_ary;
}

Returns a new array containing the items in self for which the given block is not true.

See also #delete_if

If no block is given, an Enumerator is returned instead.

reject! { |item| block } → ary or nil Show source
reject! → Enumerator
static VALUE
rb_ary_reject_bang(VALUE ary)
{
    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    return ary_reject_bang(ary);
}

Equivalent to #delete_if, deleting elements from self for which the block evaluates to true, but returns nil if no changes were made.

The array is changed instantly every time the block is called, not after the iteration is over.

See also Enumerable#reject and #delete_if.

If no block is given, an Enumerator is returned instead.

repeated_combination(n) { |c| block } → ary Show source
repeated_combination(n) → Enumerator
static VALUE
rb_ary_repeated_combination(VALUE ary, VALUE num)
{
    long n, i, len;

    n = NUM2LONG(num);                 /* Combination size from argument */
    RETURN_SIZED_ENUMERATOR(ary, 1, &num, rb_ary_repeated_combination_size);   /* Return enumerator if no block */
    len = RARRAY_LEN(ary);
    if (n < 0) {
        /* yield nothing */
    }
    else if (n == 0) {
        rb_yield(rb_ary_new2(0));
    }
    else if (n == 1) {
        for (i = 0; i < RARRAY_LEN(ary); i++) {
            rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
        }
    }
    else if (len == 0) {
        /* yield nothing */
    }
    else {
        volatile VALUE t0;
        long *p = ALLOCV_N(long, t0, n);
        VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
        RBASIC_CLEAR_CLASS(ary0);

        rcombinate0(len, n, p, n, ary0); /* compute and yield repeated combinations */
        ALLOCV_END(t0);
        RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
    }
    return ary;
}

When invoked with a block, yields all repeated combinations of length n of elements from the array and then returns the array itself.

The implementation makes no guarantees about the order in which the repeated combinations are yielded.

If no block is given, an Enumerator is returned instead.

Examples:

a = [1, 2, 3]
a.repeated_combination(1).to_a  #=> [[1], [2], [3]]
a.repeated_combination(2).to_a  #=> [[1,1],[1,2],[1,3],[2,2],[2,3],[3,3]]
a.repeated_combination(3).to_a  #=> [[1,1,1],[1,1,2],[1,1,3],[1,2,2],[1,2,3],
                                #    [1,3,3],[2,2,2],[2,2,3],[2,3,3],[3,3,3]]
a.repeated_combination(4).to_a  #=> [[1,1,1,1],[1,1,1,2],[1,1,1,3],[1,1,2,2],[1,1,2,3],
                                #    [1,1,3,3],[1,2,2,2],[1,2,2,3],[1,2,3,3],[1,3,3,3],
                                #    [2,2,2,2],[2,2,2,3],[2,2,3,3],[2,3,3,3],[3,3,3,3]]
a.repeated_combination(0).to_a  #=> [[]] # one combination of length 0
repeated_permutation(n) { |p| block } → ary Show source
repeated_permutation(n) → Enumerator
static VALUE
rb_ary_repeated_permutation(VALUE ary, VALUE num)
{
    long r, n, i;

    n = RARRAY_LEN(ary);                  /* Array length */
    RETURN_SIZED_ENUMERATOR(ary, 1, &num, rb_ary_repeated_permutation_size);      /* Return Enumerator if no block */
    r = NUM2LONG(num);                    /* Permutation size from argument */

    if (r < 0) {
        /* no permutations: yield nothing */
    }
    else if (r == 0) { /* exactly one permutation: the zero-length array */
        rb_yield(rb_ary_new2(0));
    }
    else if (r == 1) { /* this is a special, easy case */
        for (i = 0; i < RARRAY_LEN(ary); i++) {
            rb_yield(rb_ary_new3(1, RARRAY_AREF(ary, i)));
        }
    }
    else {             /* this is the general case */
        volatile VALUE t0;
        long *p = ALLOCV_N(long, t0, r);
        VALUE ary0 = ary_make_shared_copy(ary); /* private defensive copy of ary */
        RBASIC_CLEAR_CLASS(ary0);

        rpermute0(n, r, p, ary0); /* compute and yield repeated permutations */
        ALLOCV_END(t0);
        RBASIC_SET_CLASS_RAW(ary0, rb_cArray);
    }
    return ary;
}

When invoked with a block, yield all repeated permutations of length n of the elements of the array, then return the array itself.

The implementation makes no guarantees about the order in which the repeated permutations are yielded.

If no block is given, an Enumerator is returned instead.

Examples:

a = [1, 2]
a.repeated_permutation(1).to_a  #=> [[1], [2]]
a.repeated_permutation(2).to_a  #=> [[1,1],[1,2],[2,1],[2,2]]
a.repeated_permutation(3).to_a  #=> [[1,1,1],[1,1,2],[1,2,1],[1,2,2],
                                #    [2,1,1],[2,1,2],[2,2,1],[2,2,2]]
a.repeated_permutation(0).to_a  #=> [[]] # one permutation of length 0
replace(other_ary) → ary Show source
VALUE
rb_ary_replace(VALUE copy, VALUE orig)
{
    rb_ary_modify_check(copy);
    orig = to_ary(orig);
    if (copy == orig) return copy;

    if (RARRAY_LEN(orig) <= RARRAY_EMBED_LEN_MAX) {
        VALUE shared = 0;

        if (ARY_OWNS_HEAP_P(copy)) {
            RARRAY_PTR_USE(copy, ptr, ruby_sized_xfree(ptr, ARY_HEAP_SIZE(copy)));
        }
        else if (ARY_SHARED_P(copy)) {
            shared = ARY_SHARED(copy);
            FL_UNSET_SHARED(copy);
        }
        FL_SET_EMBED(copy);
        ary_memcpy(copy, 0, RARRAY_LEN(orig), RARRAY_CONST_PTR(orig));
        if (shared) {
            rb_ary_decrement_share(shared);
        }
        ARY_SET_LEN(copy, RARRAY_LEN(orig));
    }
    else {
        VALUE shared = ary_make_shared(orig);
        if (ARY_OWNS_HEAP_P(copy)) {
            RARRAY_PTR_USE(copy, ptr, ruby_sized_xfree(ptr, ARY_HEAP_SIZE(copy)));
        }
        else {
            rb_ary_unshare_safe(copy);
        }
        FL_UNSET_EMBED(copy);
        ARY_SET_PTR(copy, RARRAY_CONST_PTR(orig));
        ARY_SET_LEN(copy, RARRAY_LEN(orig));
        rb_ary_set_shared(copy, shared);
    }
    return copy;
}

Replaces the contents of self with the contents of other_ary, truncating or expanding if necessary.

a = [ "a", "b", "c", "d", "e" ]
a.replace([ "x", "y", "z" ])   #=> ["x", "y", "z"]
a                              #=> ["x", "y", "z"]
reverse → new_ary Show source
static VALUE
rb_ary_reverse_m(VALUE ary)
{
    long len = RARRAY_LEN(ary);
    VALUE dup = rb_ary_new2(len);

    if (len > 0) {
        const VALUE *p1 = RARRAY_CONST_PTR(ary);
        VALUE *p2 = (VALUE *)RARRAY_CONST_PTR(dup) + len - 1;
        do *p2-- = *p1++; while (--len > 0);
    }
    ARY_SET_LEN(dup, RARRAY_LEN(ary));
    return dup;
}

Returns a new array containing self's elements in reverse order.

[ "a", "b", "c" ].reverse   #=> ["c", "b", "a"]
[ 1 ].reverse               #=> [1]
reverse! → ary Show source
static VALUE
rb_ary_reverse_bang(VALUE ary)
{
    return rb_ary_reverse(ary);
}

Reverses self in place.

a = [ "a", "b", "c" ]
a.reverse!       #=> ["c", "b", "a"]
a                #=> ["c", "b", "a"]
reverse_each { |item| block } → ary Show source
reverse_each → Enumerator
static VALUE
rb_ary_reverse_each(VALUE ary)
{
    long len;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    len = RARRAY_LEN(ary);
    while (len--) {
        long nlen;
        rb_yield(RARRAY_AREF(ary, len));
        nlen = RARRAY_LEN(ary);
        if (nlen < len) {
            len = nlen;
        }
    }
    return ary;
}

Same as #each, but traverses self in reverse order.

a = [ "a", "b", "c" ]
a.reverse_each {|x| print x, " " }

produces:

c b a
rindex(obj) → int or nil Show source
rindex { |item| block } → int or nil
rindex → Enumerator
static VALUE
rb_ary_rindex(int argc, VALUE *argv, VALUE ary)
{
    const VALUE *ptr;
    VALUE val;
    long i = RARRAY_LEN(ary), len;

    if (argc == 0) {
        RETURN_ENUMERATOR(ary, 0, 0);
        while (i--) {
            if (RTEST(rb_yield(RARRAY_AREF(ary, i))))
                return LONG2NUM(i);
            if (i > (len = RARRAY_LEN(ary))) {
                i = len;
            }
        }
        return Qnil;
    }
    rb_check_arity(argc, 0, 1);
    val = argv[0];
    if (rb_block_given_p())
        rb_warn("given block not used");
    ptr = RARRAY_CONST_PTR(ary);
    while (i--) {
        VALUE e = ptr[i];
        switch (rb_equal_opt(e, val)) {
          case Qundef:
            if (!rb_equal(e, val)) break;
          case Qtrue:
            return LONG2NUM(i);
          case Qfalse:
            continue;
        }
        if (i > (len = RARRAY_LEN(ary))) {
            i = len;
        }
        ptr = RARRAY_CONST_PTR(ary);
    }
    return Qnil;
}

Returns the index of the last object in self == to obj.

If a block is given instead of an argument, returns the index of the first object for which the block returns true, starting from the last object.

Returns nil if no match is found.

See also #index.

If neither block nor argument is given, an Enumerator is returned instead.

a = [ "a", "b", "b", "b", "c" ]
a.rindex("b")             #=> 3
a.rindex("z")             #=> nil
a.rindex { |x| x == "b" } #=> 3
rotate(count=1) → new_ary Show source
static VALUE
rb_ary_rotate_m(int argc, VALUE *argv, VALUE ary)
{
    VALUE rotated;
    const VALUE *ptr;
    long len, cnt = 1;

    switch (argc) {
      case 1: cnt = NUM2LONG(argv[0]);
      case 0: break;
      default: rb_scan_args(argc, argv, "01", NULL);
    }

    len = RARRAY_LEN(ary);
    rotated = rb_ary_new2(len);
    if (len > 0) {
        cnt = rotate_count(cnt, len);
        ptr = RARRAY_CONST_PTR(ary);
        len -= cnt;
        ary_memcpy(rotated, 0, len, ptr + cnt);
        ary_memcpy(rotated, len, cnt, ptr);
    }
    ARY_SET_LEN(rotated, RARRAY_LEN(ary));
    return rotated;
}

Returns a new array by rotating self so that the element at count is the first element of the new array.

If count is negative then it rotates in the opposite direction, starting from the end of self where -1 is the last element.

a = [ "a", "b", "c", "d" ]
a.rotate         #=> ["b", "c", "d", "a"]
a                #=> ["a", "b", "c", "d"]
a.rotate(2)      #=> ["c", "d", "a", "b"]
a.rotate(-3)     #=> ["b", "c", "d", "a"]
rotate!(count=1) → ary Show source
static VALUE
rb_ary_rotate_bang(int argc, VALUE *argv, VALUE ary)
{
    long n = 1;

    switch (argc) {
      case 1: n = NUM2LONG(argv[0]);
      case 0: break;
      default: rb_scan_args(argc, argv, "01", NULL);
    }
    rb_ary_rotate(ary, n);
    return ary;
}

Rotates self in place so that the element at count comes first, and returns self.

If count is negative then it rotates in the opposite direction, starting from the end of the array where -1 is the last element.

a = [ "a", "b", "c", "d" ]
a.rotate!        #=> ["b", "c", "d", "a"]
a                #=> ["b", "c", "d", "a"]
a.rotate!(2)     #=> ["d", "a", "b", "c"]
a.rotate!(-3)    #=> ["a", "b", "c", "d"]
sample → obj Show source
sample(random: rng) → obj
sample(n) → new_ary
sample(n, random: rng) → new_ary
static VALUE
rb_ary_sample(int argc, VALUE *argv, VALUE ary)
{
    VALUE nv, result;
    VALUE opts, randgen = rb_cRandom;
    long n, len, i, j, k, idx[10];
    long rnds[numberof(idx)];

    if (OPTHASH_GIVEN_P(opts)) {
        VALUE rnd;
        ID keyword_ids[1];

        keyword_ids[0] = id_random;
        rb_get_kwargs(opts, keyword_ids, 0, 1, &rnd);
        if (rnd != Qundef) {
            randgen = rnd;
        }
    }
    len = RARRAY_LEN(ary);
    if (argc == 0) {
        if (len < 2)
            i = 0;
        else
            i = RAND_UPTO(len);

        return rb_ary_elt(ary, i);
    }
    rb_scan_args(argc, argv, "1", &nv);
    n = NUM2LONG(nv);
    if (n < 0) rb_raise(rb_eArgError, "negative sample number");
    if (n > len) n = len;
    if (n <= numberof(idx)) {
        for (i = 0; i < n; ++i) {
            rnds[i] = RAND_UPTO(len - i);
        }
    }
    k = len;
    len = RARRAY_LEN(ary);
    if (len < k && n <= numberof(idx)) {
        for (i = 0; i < n; ++i) {
            if (rnds[i] >= len) return rb_ary_new_capa(0);
        }
    }
    if (n > len) n = len;
    switch (n) {
      case 0:
        return rb_ary_new_capa(0);
      case 1:
        i = rnds[0];
        return rb_ary_new_from_values(1, &RARRAY_AREF(ary, i));
      case 2:
        i = rnds[0];
        j = rnds[1];
        if (j >= i) j++;
        return rb_ary_new_from_args(2, RARRAY_AREF(ary, i), RARRAY_AREF(ary, j));
      case 3:
        i = rnds[0];
        j = rnds[1];
        k = rnds[2];
        {
            long l = j, g = i;
            if (j >= i) l = i, g = ++j;
            if (k >= l && (++k >= g)) ++k;
        }
        return rb_ary_new_from_args(3, RARRAY_AREF(ary, i), RARRAY_AREF(ary, j), RARRAY_AREF(ary, k));
    }
    if (n <= numberof(idx)) {
        long sorted[numberof(idx)];
        sorted[0] = idx[0] = rnds[0];
        for (i=1; i<n; i++) {
            k = rnds[i];
            for (j = 0; j < i; ++j) {
                if (k < sorted[j]) break;
                ++k;
            }
            memmove(&sorted[j+1], &sorted[j], sizeof(sorted[0])*(i-j));
            sorted[j] = idx[i] = k;
        }
        result = rb_ary_new_capa(n);
        RARRAY_PTR_USE(result, ptr_result, {
            for (i=0; i<n; i++) {
                ptr_result[i] = RARRAY_AREF(ary, idx[i]);
            }
        });
    }
    else {
        result = rb_ary_dup(ary);
        RBASIC_CLEAR_CLASS(result);
        RB_GC_GUARD(ary);
        RARRAY_PTR_USE(result, ptr_result, {
            for (i=0; i<n; i++) {
                j = RAND_UPTO(len-i) + i;
                nv = ptr_result[j];
                ptr_result[j] = ptr_result[i];
                ptr_result[i] = nv;
            }
        });
        RBASIC_SET_CLASS_RAW(result, rb_cArray);
    }
    ARY_SET_LEN(result, n);

    return result;
}

Choose a random element or n random elements from the array.

The elements are chosen by using random and unique indices into the array in order to ensure that an element doesn't repeat itself unless the array already contained duplicate elements.

If the array is empty the first form returns nil and the second form returns an empty array.

The optional rng argument will be used as the random number generator.

a = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]
a.sample         #=> 7
a.sample(4)      #=> [6, 4, 2, 5]
select { |item| block } → new_ary Show source
select → Enumerator
static VALUE
rb_ary_select(VALUE ary)
{
    VALUE result;
    long i;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    result = rb_ary_new2(RARRAY_LEN(ary));
    for (i = 0; i < RARRAY_LEN(ary); i++) {
        if (RTEST(rb_yield(RARRAY_AREF(ary, i)))) {
            rb_ary_push(result, rb_ary_elt(ary, i));
        }
    }
    return result;
}

Returns a new array containing all elements of ary for which the given block returns a true value.

If no block is given, an Enumerator is returned instead.

[1,2,3,4,5].select { |num|  num.even?  }   #=> [2, 4]

a = %w{ a b c d e f }
a.select { |v| v =~ /[aeiou]/ }  #=> ["a", "e"]

See also Enumerable#select.

select! {|item| block } → ary or nil Show source
select! → Enumerator
static VALUE
rb_ary_select_bang(VALUE ary)
{
    long i1, i2;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    rb_ary_modify(ary);
    for (i1 = i2 = 0; i1 < RARRAY_LEN(ary); i1++) {
        VALUE v = RARRAY_AREF(ary, i1);
        if (!RTEST(rb_yield(v))) continue;
        if (i1 != i2) {
            rb_ary_store(ary, i2, v);
        }
        i2++;
    }

    if (i1 == i2) return Qnil;
    if (i2 < i1)
        ARY_SET_LEN(ary, i2);
    return ary;
}

Invokes the given block passing in successive elements from self, deleting elements for which the block returns a false value.

If changes were made, it will return self, otherwise it returns nil.

See also #keep_if

If no block is given, an Enumerator is returned instead.

shelljoin → string Show source
# File lib/shellwords.rb, line 212
def shelljoin
  Shellwords.join(self)
end

Builds a command line string from an argument list array joining all elements escaped for the Bourne shell and separated by a space.

See Shellwords#shelljoin for details.

shift → obj or nil Show source
shift(n) → new_ary
static VALUE
rb_ary_shift_m(int argc, VALUE *argv, VALUE ary)
{
    VALUE result;
    long n;

    if (argc == 0) {
        return rb_ary_shift(ary);
    }

    rb_ary_modify_check(ary);
    result = ary_take_first_or_last(argc, argv, ary, ARY_TAKE_FIRST);
    n = RARRAY_LEN(result);
    if (ARY_SHARED_P(ary)) {
        if (ARY_SHARED_OCCUPIED(ARY_SHARED(ary))) {
            ary_mem_clear(ary, 0, n);
        }
        ARY_INCREASE_PTR(ary, n);
    }
    else {
        RARRAY_PTR_USE(ary, ptr, {
            MEMMOVE(ptr, ptr + n, VALUE, RARRAY_LEN(ary)-n);
        }); /* WB: no new reference */
    }
    ARY_INCREASE_LEN(ary, -n);

    return result;
}

Removes the first element of self and returns it (shifting all other elements down by one). Returns nil if the array is empty.

If a number n is given, returns an array of the first n elements (or less) just like array.slice!(0, n) does. With ary containing only the remainder elements, not including what was shifted to new_ary. See also #unshift for the opposite effect.

args = [ "-m", "-q", "filename" ]
args.shift     #=> "-m"
args           #=> ["-q", "filename"]

args = [ "-m", "-q", "filename" ]
args.shift(2)  #=> ["-m", "-q"]
args           #=> ["filename"]
shuffle → new_ary Show source
shuffle(random: rng) → new_ary
static VALUE
rb_ary_shuffle(int argc, VALUE *argv, VALUE ary)
{
    ary = rb_ary_dup(ary);
    rb_ary_shuffle_bang(argc, argv, ary);
    return ary;
}

Returns a new array with elements of self shuffled.

a = [ 1, 2, 3 ]           #=> [1, 2, 3]
a.shuffle                 #=> [2, 3, 1]
a                         #=> [1, 2, 3]

The optional rng argument will be used as the random number generator.

a.shuffle(random: Random.new(1))  #=> [1, 3, 2]
shuffle! → ary Show source
shuffle!(random: rng) → ary
static VALUE
rb_ary_shuffle_bang(int argc, VALUE *argv, VALUE ary)
{
    VALUE opts, randgen = rb_cRandom;
    long i, len;

    if (OPTHASH_GIVEN_P(opts)) {
        VALUE rnd;
        ID keyword_ids[1];

        keyword_ids[0] = id_random;
        rb_get_kwargs(opts, keyword_ids, 0, 1, &rnd);
        if (rnd != Qundef) {
            randgen = rnd;
        }
    }
    rb_check_arity(argc, 0, 0);
    rb_ary_modify(ary);
    i = len = RARRAY_LEN(ary);
    RARRAY_PTR_USE(ary, ptr, {
        while (i) {
            long j = RAND_UPTO(i);
            VALUE tmp;
            if (len != RARRAY_LEN(ary) || ptr != RARRAY_CONST_PTR(ary)) {
                rb_raise(rb_eRuntimeError, "modified during shuffle");
            }
            tmp = ptr[--i];
            ptr[i] = ptr[j];
            ptr[j] = tmp;
        }
    }); /* WB: no new reference */
    return ary;
}

Shuffles elements in self in place.

a = [ 1, 2, 3 ]           #=> [1, 2, 3]
a.shuffle!                #=> [2, 3, 1]
a                         #=> [2, 3, 1]

The optional rng argument will be used as the random number generator.

a.shuffle!(random: Random.new(1))  #=> [1, 3, 2]
size()
Alias for: length
slice(index) → obj or nil Show source
slice(start, length) → new_ary or nil
slice(range) → new_ary or nil
VALUE
rb_ary_aref(int argc, const VALUE *argv, VALUE ary)
{
    VALUE arg;
    long beg, len;

    if (argc == 2) {
        beg = NUM2LONG(argv[0]);
        len = NUM2LONG(argv[1]);
        if (beg < 0) {
            beg += RARRAY_LEN(ary);
        }
        return rb_ary_subseq(ary, beg, len);
    }
    if (argc != 1) {
        rb_scan_args(argc, argv, "11", NULL, NULL);
    }
    arg = argv[0];
    /* special case - speeding up */
    if (FIXNUM_P(arg)) {
        return rb_ary_entry(ary, FIX2LONG(arg));
    }
    /* check if idx is Range */
    switch (rb_range_beg_len(arg, &beg, &len, RARRAY_LEN(ary), 0)) {
      case Qfalse:
        break;
      case Qnil:
        return Qnil;
      default:
        return rb_ary_subseq(ary, beg, len);
    }
    return rb_ary_entry(ary, NUM2LONG(arg));
}

Element Reference — Returns the element at index, or returns a subarray starting at the start index and continuing for length elements, or returns a subarray specified by range of indices.

Negative indices count backward from the end of the array (-1 is the last element). For start and range cases the starting index is just before an element. Additionally, an empty array is returned when the starting index for an element range is at the end of the array.

Returns nil if the index (or starting index) are out of range.

a = [ "a", "b", "c", "d", "e" ]
a[2] +  a[0] + a[1]    #=> "cab"
a[6]                   #=> nil
a[1, 2]                #=> [ "b", "c" ]
a[1..3]                #=> [ "b", "c", "d" ]
a[4..7]                #=> [ "e" ]
a[6..10]               #=> nil
a[-3, 3]               #=> [ "c", "d", "e" ]
# special cases
a[5]                   #=> nil
a[6, 1]                #=> nil
a[5, 1]                #=> []
a[5..10]               #=> []
slice!(index) → obj or nil Show source
slice!(start, length) → new_ary or nil
slice!(range) → new_ary or nil
static VALUE
rb_ary_slice_bang(int argc, VALUE *argv, VALUE ary)
{
    VALUE arg1, arg2;
    long pos, len, orig_len;

    rb_ary_modify_check(ary);
    if (argc == 2) {
        pos = NUM2LONG(argv[0]);
        len = NUM2LONG(argv[1]);
      delete_pos_len:
        if (len < 0) return Qnil;
        orig_len = RARRAY_LEN(ary);
        if (pos < 0) {
            pos += orig_len;
            if (pos < 0) return Qnil;
        }
        else if (orig_len < pos) return Qnil;
        if (orig_len < pos + len) {
            len = orig_len - pos;
        }
        if (len == 0) return rb_ary_new2(0);
        arg2 = rb_ary_new4(len, RARRAY_CONST_PTR(ary)+pos);
        RBASIC_SET_CLASS(arg2, rb_obj_class(ary));
        rb_ary_splice(ary, pos, len, Qundef);
        return arg2;
    }

    if (argc != 1) {
        /* error report */
        rb_scan_args(argc, argv, "11", NULL, NULL);
    }
    arg1 = argv[0];

    if (!FIXNUM_P(arg1)) {
        switch (rb_range_beg_len(arg1, &pos, &len, RARRAY_LEN(ary), 0)) {
          case Qtrue:
            /* valid range */
            goto delete_pos_len;
          case Qnil:
            /* invalid range */
            return Qnil;
          default:
            /* not a range */
            break;
        }
    }

    return rb_ary_delete_at(ary, NUM2LONG(arg1));
}

Deletes the element(s) given by an index (optionally up to length elements) or by a range.

Returns the deleted object (or objects), or nil if the index is out of range.

a = [ "a", "b", "c" ]
a.slice!(1)     #=> "b"
a               #=> ["a", "c"]
a.slice!(-1)    #=> "c"
a               #=> ["a"]
a.slice!(100)   #=> nil
a               #=> ["a"]
sort → new_ary Show source
sort { |a, b| block } → new_ary
VALUE
rb_ary_sort(VALUE ary)
{
    ary = rb_ary_dup(ary);
    rb_ary_sort_bang(ary);
    return ary;
}

Returns a new array created by sorting self.

Comparisons for the sort will be done using the <=> operator or using an optional code block.

The block must implement a comparison between a and b, and return -1, when a follows b, 0 when a and b are equivalent, or +1 if b follows a.

See also Enumerable#sort_by.

a = [ "d", "a", "e", "c", "b" ]
a.sort                    #=> ["a", "b", "c", "d", "e"]
a.sort { |x,y| y <=> x }  #=> ["e", "d", "c", "b", "a"]
sort! → ary Show source
sort! { |a, b| block } → ary
VALUE
rb_ary_sort_bang(VALUE ary)
{
    rb_ary_modify(ary);
    assert(!ARY_SHARED_P(ary));
    if (RARRAY_LEN(ary) > 1) {
        VALUE tmp = ary_make_substitution(ary); /* only ary refers tmp */
        struct ary_sort_data data;
        long len = RARRAY_LEN(ary);

        RBASIC_CLEAR_CLASS(tmp);
        data.ary = tmp;
        data.opt_methods = 0;
        data.opt_inited = 0;
        RARRAY_PTR_USE(tmp, ptr, {
            ruby_qsort(ptr, len, sizeof(VALUE),
                       rb_block_given_p()?sort_1:sort_2, &data);
        }); /* WB: no new reference */
        rb_ary_modify(ary);
        if (ARY_EMBED_P(tmp)) {
            if (ARY_SHARED_P(ary)) { /* ary might be destructively operated in the given block */
                rb_ary_unshare(ary);
            }
            FL_SET_EMBED(ary);
            ary_memcpy(ary, 0, ARY_EMBED_LEN(tmp), ARY_EMBED_PTR(tmp));
            ARY_SET_LEN(ary, ARY_EMBED_LEN(tmp));
        }
        else {
            if (!ARY_EMBED_P(ary) && ARY_HEAP_PTR(ary) == ARY_HEAP_PTR(tmp)) {
                FL_UNSET_SHARED(ary);
                ARY_SET_CAPA(ary, RARRAY_LEN(tmp));
            }
            else {
                assert(!ARY_SHARED_P(tmp));
                if (ARY_EMBED_P(ary)) {
                    FL_UNSET_EMBED(ary);
                }
                else if (ARY_SHARED_P(ary)) {
                    /* ary might be destructively operated in the given block */
                    rb_ary_unshare(ary);
                }
                else {
                    ruby_sized_xfree((void *)ARY_HEAP_PTR(ary), ARY_HEAP_SIZE(ary));
                }
                ARY_SET_PTR(ary, RARRAY_CONST_PTR(tmp));
                ARY_SET_HEAP_LEN(ary, len);
                ARY_SET_CAPA(ary, RARRAY_LEN(tmp));
            }
            /* tmp was lost ownership for the ptr */
            FL_UNSET(tmp, FL_FREEZE);
            FL_SET_EMBED(tmp);
            ARY_SET_EMBED_LEN(tmp, 0);
            FL_SET(tmp, FL_FREEZE);
        }
        /* tmp will be GC'ed. */
        RBASIC_SET_CLASS_RAW(tmp, rb_cArray); /* rb_cArray must be marked */
    }
    return ary;
}

Sorts self in place.

Comparisons for the sort will be done using the <=> operator or using an optional code block.

The block must implement a comparison between a and b, and return -1, when a follows b, 0 when a and b are equivalent, or +1 if b follows a.

See also Enumerable#sort_by.

a = [ "d", "a", "e", "c", "b" ]
a.sort!                    #=> ["a", "b", "c", "d", "e"]
a.sort! { |x,y| y <=> x }  #=> ["e", "d", "c", "b", "a"]
sort_by! { |obj| block } → ary Show source
sort_by! → Enumerator
static VALUE
rb_ary_sort_by_bang(VALUE ary)
{
    VALUE sorted;

    RETURN_SIZED_ENUMERATOR(ary, 0, 0, ary_enum_length);
    rb_ary_modify(ary);
    sorted = rb_block_call(ary, rb_intern("sort_by"), 0, 0, sort_by_i, 0);
    rb_ary_replace(ary, sorted);
    return ary;
}

Sorts self in place using a set of keys generated by mapping the values in self through the given block.

If no block is given, an Enumerator is returned instead.

take(n) → new_ary Show source
static VALUE
rb_ary_take(VALUE obj, VALUE n)
{
    long len = NUM2LONG(n);
    if (len < 0) {
        rb_raise(rb_eArgError, "attempt to take negative size");
    }
    return rb_ary_subseq(obj, 0, len);
}

Returns first n elements from the array.

If a negative number is given, raises an ArgumentError.

See also #drop

a = [1, 2, 3, 4, 5, 0]
a.take(3)             #=> [1, 2, 3]
take_while { |arr| block } → new_ary Show source
take_while → Enumerator
static VALUE
rb_ary_take_while(VALUE ary)
{
    long i;

    RETURN_ENUMERATOR(ary, 0, 0);
    for (i = 0; i < RARRAY_LEN(ary); i++) {
        if (!RTEST(rb_yield(RARRAY_AREF(ary, i)))) break;
    }
    return rb_ary_take(ary, LONG2FIX(i));
}

Passes elements to the block until the block returns nil or false, then stops iterating and returns an array of all prior elements.

If no block is given, an Enumerator is returned instead.

See also #drop_while

a = [1, 2, 3, 4, 5, 0]
a.take_while { |i| i < 3 }  #=> [1, 2]
to_a → ary Show source
static VALUE
rb_ary_to_a(VALUE ary)
{
    if (rb_obj_class(ary) != rb_cArray) {
        VALUE dup = rb_ary_new2(RARRAY_LEN(ary));
        rb_ary_replace(dup, ary);
        return dup;
    }
    return ary;
}

Returns self.

If called on a subclass of Array, converts the receiver to an Array object.

to_ary → ary Show source
static VALUE
rb_ary_to_ary_m(VALUE ary)
{
    return ary;
}

Returns self.

to_h → hash Show source
static VALUE
rb_ary_to_h(VALUE ary)
{
    long i;
    VALUE hash = rb_hash_new();
    for (i=0; i<RARRAY_LEN(ary); i++) {
        VALUE key_value_pair = rb_check_array_type(rb_ary_elt(ary, i));
        if (NIL_P(key_value_pair)) {
            rb_raise(rb_eTypeError, "wrong element type %s at %ld (expected array)",
                rb_builtin_class_name(rb_ary_elt(ary, i)), i);
        }
        if (RARRAY_LEN(key_value_pair) != 2) {
            rb_raise(rb_eArgError, "wrong array length at %ld (expected 2, was %ld)",
                i, RARRAY_LEN(key_value_pair));
        }
        rb_hash_aset(hash, RARRAY_AREF(key_value_pair, 0), RARRAY_AREF(key_value_pair, 1));
    }
    return hash;
}

Returns the result of interpreting ary as an array of [key, value] pairs.

[[:foo, :bar], [1, 2]].to_h
  # => {:foo => :bar, 1 => 2}
to_s()
Alias for: inspect
transpose → new_ary Show source
static VALUE
rb_ary_transpose(VALUE ary)
{
    long elen = -1, alen, i, j;
    VALUE tmp, result = 0;

    alen = RARRAY_LEN(ary);
    if (alen == 0) return rb_ary_dup(ary);
    for (i=0; i<alen; i++) {
        tmp = to_ary(rb_ary_elt(ary, i));
        if (elen < 0) {                /* first element */
            elen = RARRAY_LEN(tmp);
            result = rb_ary_new2(elen);
            for (j=0; j<elen; j++) {
                rb_ary_store(result, j, rb_ary_new2(alen));
            }
        }
        else if (elen != RARRAY_LEN(tmp)) {
            rb_raise(rb_eIndexError, "element size differs (%ld should be %ld)",
                     RARRAY_LEN(tmp), elen);
        }
        for (j=0; j<elen; j++) {
            rb_ary_store(rb_ary_elt(result, j), i, rb_ary_elt(tmp, j));
        }
    }
    return result;
}

Assumes that self is an array of arrays and transposes the rows and columns.

a = [[1,2], [3,4], [5,6]]
a.transpose   #=> [[1, 3, 5], [2, 4, 6]]

If the length of the subarrays don't match, an IndexError is raised.

uniq → new_ary Show source
uniq { |item| ... } → new_ary
static VALUE
rb_ary_uniq(VALUE ary)
{
    VALUE hash, uniq;

    if (RARRAY_LEN(ary) <= 1)
        return rb_ary_dup(ary);
    if (rb_block_given_p()) {
        hash = ary_make_hash_by(ary);
        uniq = rb_hash_values(hash);
    }
    else {
        hash = ary_make_hash(ary);
        uniq = rb_hash_values(hash);
    }
    RBASIC_SET_CLASS(uniq, rb_obj_class(ary));
    ary_recycle_hash(hash);

    return uniq;
}

Returns a new array by removing duplicate values in self.

If a block is given, it will use the return value of the block for comparison.

It compares values using their hash and eql? methods for efficiency.

a = [ "a", "a", "b", "b", "c" ]
a.uniq   # => ["a", "b", "c"]

b = [["student","sam"], ["student","george"], ["teacher","matz"]]
b.uniq { |s| s.first } # => [["student", "sam"], ["teacher", "matz"]]
uniq! → ary or nil Show source
uniq! { |item| ... } → ary or nil
static VALUE
rb_ary_uniq_bang(VALUE ary)
{
    VALUE hash;
    long hash_size;

    rb_ary_modify_check(ary);
    if (RARRAY_LEN(ary) <= 1)
        return Qnil;
    if (rb_block_given_p())
        hash = ary_make_hash_by(ary);
    else
        hash = ary_make_hash(ary);

    hash_size = RHASH_SIZE(hash);
    if (RARRAY_LEN(ary) == hash_size) {
        return Qnil;
    }
    rb_ary_modify_check(ary);
    ARY_SET_LEN(ary, 0);
    if (ARY_SHARED_P(ary) && !ARY_EMBED_P(ary)) {
        rb_ary_unshare(ary);
        FL_SET_EMBED(ary);
    }
    ary_resize_capa(ary, hash_size);
    st_foreach(rb_hash_tbl_raw(hash), push_value, ary);
    ary_recycle_hash(hash);

    return ary;
}

Removes duplicate elements from self.

If a block is given, it will use the return value of the block for comparison.

It compares values using their hash and eql? methods for efficiency.

Returns nil if no changes are made (that is, no duplicates are found).

a = [ "a", "a", "b", "b", "c" ]
a.uniq!   # => ["a", "b", "c"]

b = [ "a", "b", "c" ]
b.uniq!   # => nil

c = [["student","sam"], ["student","george"], ["teacher","matz"]]
c.uniq! { |s| s.first } # => [["student", "sam"], ["teacher", "matz"]]
unshift(obj, ...) → ary Show source
static VALUE
rb_ary_unshift_m(int argc, VALUE *argv, VALUE ary)
{
    long len = RARRAY_LEN(ary);
    VALUE target_ary;

    if (argc == 0) {
        rb_ary_modify_check(ary);
        return ary;
    }

    target_ary = ary_ensure_room_for_unshift(ary, argc);
    ary_memcpy0(ary, 0, argc, argv, target_ary);
    ARY_SET_LEN(ary, len + argc);
    return ary;
}

Prepends objects to the front of self, moving other elements upwards. See also #shift for the opposite effect.

a = [ "b", "c", "d" ]
a.unshift("a")   #=> ["a", "b", "c", "d"]
a.unshift(1, 2)  #=> [ 1, 2, "a", "b", "c", "d"]
values_at(selector, ...) → new_ary Show source
static VALUE
rb_ary_values_at(int argc, VALUE *argv, VALUE ary)
{
    return rb_get_values_at(ary, RARRAY_LEN(ary), argc, argv, rb_ary_entry);
}

Returns an array containing the elements in self corresponding to the given selector(s).

The selectors may be either integer indices or ranges.

See also #select.

a = %w{ a b c d e f }
a.values_at(1, 3, 5)          # => ["b", "d", "f"]
a.values_at(1, 3, 5, 7)       # => ["b", "d", "f", nil]
a.values_at(-1, -2, -2, -7)   # => ["f", "e", "e", nil]
a.values_at(4..6, 3...6)      # => ["e", "f", nil, "d", "e", "f"]
zip(arg, ...) → new_ary Show source
zip(arg, ...) { |arr| block } → nil
static VALUE
rb_ary_zip(int argc, VALUE *argv, VALUE ary)
{
    int i, j;
    long len = RARRAY_LEN(ary);
    VALUE result = Qnil;

    for (i=0; i<argc; i++) {
        argv[i] = take_items(argv[i], len);
    }

    if (rb_block_given_p()) {
        int arity = rb_block_arity();

        if (arity > 1) {
            VALUE work, *tmp;

            tmp = ALLOCV_N(VALUE, work, argc+1);

            for (i=0; i<RARRAY_LEN(ary); i++) {
                tmp[0] = RARRAY_AREF(ary, i);
                for (j=0; j<argc; j++) {
                    tmp[j+1] = rb_ary_elt(argv[j], i);
                }
                rb_yield_values2(argc+1, tmp);
            }

            if (work) ALLOCV_END(work);
        }
        else {
            for (i=0; i<RARRAY_LEN(ary); i++) {
                VALUE tmp = rb_ary_new2(argc+1);

                rb_ary_push(tmp, RARRAY_AREF(ary, i));
                for (j=0; j<argc; j++) {
                    rb_ary_push(tmp, rb_ary_elt(argv[j], i));
                }
                rb_yield(tmp);
            }
        }
    }
    else {
        result = rb_ary_new_capa(len);

        for (i=0; i<len; i++) {
            VALUE tmp = rb_ary_new_capa(argc+1);

            rb_ary_push(tmp, RARRAY_AREF(ary, i));
            for (j=0; j<argc; j++) {
                rb_ary_push(tmp, rb_ary_elt(argv[j], i));
            }
            rb_ary_push(result, tmp);
        }
    }

    return result;
}

Converts any arguments to arrays, then merges elements of self with corresponding elements from each argument.

This generates a sequence of ary.size n-element arrays, where n is one more than the count of arguments.

If the size of any argument is less than the size of the initial array, nil values are supplied.

If a block is given, it is invoked for each output array, otherwise an array of arrays is returned.

a = [ 4, 5, 6 ]
b = [ 7, 8, 9 ]
[1, 2, 3].zip(a, b)   #=> [[1, 4, 7], [2, 5, 8], [3, 6, 9]]
[1, 2].zip(a, b)      #=> [[1, 4, 7], [2, 5, 8]]
a.zip([1, 2], [8])    #=> [[4, 1, 8], [5, 2, nil], [6, nil, nil]]
ary | other_ary → new_ary Show source
static VALUE
rb_ary_or(VALUE ary1, VALUE ary2)
{
    VALUE hash, ary3;
    long i;

    ary2 = to_ary(ary2);
    hash = ary_make_hash(ary1);

    for (i=0; i<RARRAY_LEN(ary2); i++) {
        VALUE elt = RARRAY_AREF(ary2, i);
        if (!st_update(RHASH_TBL_RAW(hash), (st_data_t)elt, ary_hash_orset, (st_data_t)elt)) {
            RB_OBJ_WRITTEN(hash, Qundef, elt);
        }
    }
    ary3 = rb_hash_values(hash);
    ary_recycle_hash(hash);
    return ary3;
}

Set Union — Returns a new array by joining ary with other_ary, excluding any duplicates and preserving the order from the original array.

It compares elements using their hash and eql? methods for efficiency.

[ "a", "b", "c" ] | [ "c", "d", "a" ]    #=> [ "a", "b", "c", "d" ]

See also #uniq.

Ruby Core © 1993–2017 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.