std::basic_string::size, std::basic_string::length

From cppreference.com
< cpplrm; | stringlrm; | basic string
std::basic_string
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""); // 8 code points
    assert(8 == a.size()); // 8 code units in UTF-32

    std::u16string b(u""); // 8 code points
    assert(8 == b.size()); // 8 code units in UTF-16

    std::string c(u8""); // 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)