std::filesystem::path::c_str,std::filesystem::path::native, (3) - Linux Manuals

std::filesystem::path::c_str,std::filesystem::path::native,: std::filesystem::path::c_str,std::filesystem::path::native,

NAME

std::filesystem::path::c_str,std::filesystem::path::native, - std::filesystem::path::c_str,std::filesystem::path::native,

Synopsis

const value_type* c_str() const noexcept;   (1) (since C++17)
const string_type& native() const noexcept; (2) (since C++17)
operator string_type() const;               (3) (since C++17)

Accesses the native path name as a character string.

1) Equivalent to native().c_str().
2) Returns the native-format representation of the pathname by reference.
3) Returns the native-format representation of the pathname by value.

Parameters

(none)

Return value

The native string representation of the pathname, using native syntax, native
character type, and native character encoding. This string is suitable for use with
OS APIs.

Notes

The conversion function (3) is provided so that APIs that accept std::basic_string
file names can use pathnames with no changes to code.

Example

// Run this code

 #include <cstdio>
 #ifdef _MSC_VER
 #include <io.h>
 #include <fcntl.h>
 #else
 #include <locale>
 #include <clocale>
 #endif
 #include <fstream>
 #include <iostream>
 #include <filesystem>
 namespace fs = std::filesystem;

 int main()
 {
 #ifdef _MSC_VER
  _setmode(_fileno(stderr), _O_WTEXT);
 #else
  std::setlocale(LC_ALL, "");
  std::locale::global(std::locale(""));
  std::cout.imbue(std::locale());
  std::wcerr.imbue(std::locale());
 #endif

  fs::path p = fs::u8path(u8"要らない.txt");
  std::ofstream(p) << "File contents"; // Prior to LWG2676 uses operator string_type()
                                 // on MSVC, where string_type is wstring, only
                                 // works due to non-standard extension.
                                 // Post-LWG2676 uses new fstream constructors

  // native string representation can be used with OS APIs
  if (std::FILE* f =
 #ifdef _MSC_VER
        _wfopen(p.c_str(), L"r")
 #else
        std::fopen(p.c_str(), "r")
 #endif
)
  {
int ch;
while((ch=fgetc(f))!= EOF) putchar(ch);
std::fclose(f);
  }

  // multibyte and wide representation can be used for output
  std::cout << "\nFile name in narrow multibyte encoding: " << p.string() << '\n';
  std::wcerr << "File name in wide encoding: " << p.wstring() << '\n';

  fs::remove(p);
 }

Output:

 File contents
 File name in narrow multibyte encoding: 要らない.txt
 File name in wide encoding: 要らない.txt