NAME¶

std::basic_string::operatorbasic_string_view - std::basic_string::operatorbasic_string_view

Synopsis¶

operator std::basic_string_view<CharT, Traits>() const (since C++17)
noexcept; (constexpr since C++20)

Returns a std::basic_string_view, constructed as if by std::basic_string_view<CharT,
Traits>(data(), size()).

Parameters¶

(none)

Return value¶

A string view representing the entire contents of the string.

Notes¶

It is the programmer's responsibility to ensure that the resulting string view does
not outlive the string.

std::string get_string();
int f(std::string_view sv);

int x = f(get_string()); // OK
std::string_view sv = get_string(); // Bad: holds a dangling pointer

Example¶

// Run this code

#include <iostream>
#include <string>
#include <string_view>

void show_wstring_size(std::wstring_view wcstr_v)
{
std::cout << wcstr_v.size() << " code points\n";
}

int main()
{
std::string cppstr = "ラーメン"; // narrow string
std::wstring wcstr = L"ラーメン"; // wide string

// Implicit conversion from string to string_view
// via std::string::operator string_view:
std::string_view cppstr_v = cppstr;

std::cout << cppstr_v << '\n'
<< cppstr_v.size() << " code units\n";

// Implicit conversion from wstring to wstring_view
// via std::wstring::operator wstring_view:
show_wstring_size(wcstr);
}

Output:¶

ラーメン
12 code units
4 code points

See also¶

constructs a basic_string_view
constructor (public member function of std::basic_string_view<CharT,Traits>)