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std::basic_string<CharT,Traits,Allocator>::operator basic_string_view

From cppreference.com
< cpp‎ | string‎ | basic string
 
C++
 
Strings library
 
std::basic_string
 
operator std::basic_string_view<CharT, Traits>() const noexcept;
 (since C++17)
(constexpr since C++20)

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

Contents

[edit] Parameters

(none)

[edit] Return value

A string view representing the entire contents of the string.

[edit] 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

[edit] 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

[edit] See also

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