substr
(PHP 4, PHP 5, PHP 7)
substr — Return part of a string
Description
substr ( string $string , int $offset [, int|null $length = null ] ) : string
Returns the portion of string
specified by the offset
and length
parameters.
Parameters
-
string
-
The input string.
-
offset
-
If
offset
is non-negative, the returned string will start at theoffset
'th position instring
, counting from zero. For instance, in the string 'abcdef
', the character at position0
is 'a
', the character at position2
is 'c
', and so forth.If
offset
is negative, the returned string will start at theoffset
'th character from the end ofstring
.If
string
is less thanoffset
characters long,false
will be returned.Example #1 Using a negative
offset
<?php $rest = substr("abcdef", -1); // returns "f" $rest = substr("abcdef", -2); // returns "ef" $rest = substr("abcdef", -3, 1); // returns "d" ?>
-
length
-
If
length
is given and is positive, the string returned will contain at mostlength
characters beginning fromoffset
(depending on the length ofstring
).If
length
is given and is negative, then that many characters will be omitted from the end ofstring
(after the start position has been calculated when aoffset
is negative). Ifoffset
denotes the position of this truncation or beyond,false
will be returned.If
length
is given and is0
,false
ornull
, an empty string will be returned.If
length
is omitted, the substring starting fromoffset
until the end of the string will be returned.Example #2 Using a negative
length
<?php $rest = substr("abcdef", 0, -1); // returns "abcde" $rest = substr("abcdef", 2, -1); // returns "cde" $rest = substr("abcdef", 4, -4); // returns false $rest = substr("abcdef", -3, -1); // returns "de" ?>
Return Values
Returns the extracted part of string
; or false
on failure, or an empty string.
Changelog
Version | Description |
---|---|
8.0.0 | length is nullable now. |
8.0.0 | The function returns an empty where it previously returned false . |
Examples
Example #3 Basic substr() usage
<?php echo substr('abcdef', 1); // bcdef echo substr('abcdef', 1, 3); // bcd echo substr('abcdef', 0, 4); // abcd echo substr('abcdef', 0, 8); // abcdef echo substr('abcdef', -1, 1); // f // Accessing single characters in a string // can also be achieved using "square brackets" $string = 'abcdef'; echo $string[0]; // a echo $string[3]; // d echo $string[strlen($string)-1]; // f ?>
Example #4 substr() casting behaviour
<?php class apple { public function __toString() { return "green"; } } echo "1) ".var_export(substr("pear", 0, 2), true).PHP_EOL; echo "2) ".var_export(substr(54321, 0, 2), true).PHP_EOL; echo "3) ".var_export(substr(new apple(), 0, 2), true).PHP_EOL; echo "4) ".var_export(substr(true, 0, 1), true).PHP_EOL; echo "5) ".var_export(substr(false, 0, 1), true).PHP_EOL; echo "6) ".var_export(substr("", 0, 1), true).PHP_EOL; echo "7) ".var_export(substr(1.2e3, 0, 4), true).PHP_EOL; ?>
Output of the above example in PHP 7:
1) 'pe' 2) '54' 3) 'gr' 4) '1' 5) '' 6) '' 7) '1200'
Output of the above example in PHP 5:
1) 'pe' 2) '54' 3) 'gr' 4) '1' 5) false 6) false 7) '1200'
Errors/Exceptions
Returns false
on error.
<?php var_dump(substr('a', 2)); // bool(false) ?>
See Also
- strrchr() - Find the last occurrence of a character in a string
- substr_replace() - Replace text within a portion of a string
- preg_match() - Perform a regular expression match
- trim() - Strip whitespace (or other characters) from the beginning and end of a string
- mb_substr() - Get part of string
- wordwrap() - Wraps a string to a given number of characters
- String access and modification by character
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Licensed under the Creative Commons Attribution License v3.0 or later.
https://www.php.net/manual/en/function.substr.php