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size_type size()const; | (1) | (noexcept since C++11) (constexpr since C++20) |
size_type length()const; | (2) | (noexcept since C++11) (constexpr since C++20) |
Returns the number ofCharT elements in the string, i.e.std::distance(begin(), end()).
Contents |
(none)
The number ofCharT elements in the string.
Unspecified | (until C++11) |
Constant | (since C++11) |
Forstd::string, the elements are bytes (objects of typechar), which are not the same as characters if a multibyte encoding such as UTF-8 is used.
#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 pointsassert(8== a.size());// 8 code units in UTF-32 std::u16string b(u"ハロー・ワールド");// 8 code pointsassert(8== b.size());// 8 code units in UTF-16 std::string c("ハロー・ワールド");// 8 code pointsassert(24== c.size());// 24 code units in UTF-8 #if __cpp_lib_char8_t >= 201907Lstd::u8string d(u8"ハロー・ワールド");// 8 code pointsassert(24== d.size());// 24 code units in UTF-8#endif}
| checks whether the string is empty (public member function)[edit] | |
| returns the maximum number of characters (public member function)[edit] | |
| returns the number of characters (public member function of std::basic_string_view<CharT,Traits>)[edit] |
