std::basic_string<CharT,Traits,Allocator>::size, std::basic_string<CharT,Traits,Allocator>::length
size_type size() const;
| (until C++11) | |
size_type size() const noexcept;
| (since C++11) | |
size_type length() const;
| (until C++11) | |
size_type length() const noexcept;
| (since C++11) |
Returns the number of CharT
elements in the string, i.e. std::distance(begin(), end())
.
Parameters
(none).
Return value
The number of CharT
elements in the string.
Complexity
Unspecified. | (until C++11) |
Constant. | (since C++11) |
Notes
For std::string
, the elements are bytes (objects of type char), which are not the same as characters if a multibyte encoding such as UTF-8 is used.
Example
#include <cassert>
#include <iterator>
#include <string>
int main()
{
std::string s("Exemplar");
assert(8 == s.size());
assert(s.size() == s.length());
assert(s.size() == static_cast<std::string::size_type>(
std::distance(s.begin(), s.end())));
std::u32string a(U"ハロー・ワールド"); // 8 code points
assert(8 == a.size()); // 8 code units in UTF-32
std::u16string b(u"ハロー・ワールド"); // 8 code points
assert(8 == b.size()); // 8 code units in UTF-16
std::string c(u8"ハロー・ワールド"); // 8 code points
assert(24 == c.size()); // 24 code units in UTF-8
}
See also
checks whether the string is empty (public member function) |
|
returns the maximum number of characters (public member function) |
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