home | help 
std::filesy..._error::what(3)  C++ Standard Libary std::filesy..._error::what(3)

NAME
     std::filesystem::filesystem_error::what  -  std::filesystem::filesystem_er-
     ror::what

Synopsis
	const char* what() const noexcept override;  (since C++17)

	Returns an explanatory byte string. This explanatory string contains the
     explanatory
	string passed at the time of construction. Implementations  are  encour-
     aged to include
	the pathnames of path1() and path2() in native format and the
	std::system_error::what() string inside the returned string as well.

Parameters
	(none)

Return value
	A  C-stye  explanatory	byte string that contains the explanatory string
     passed at the
	time of construction.

Example
     // Run this code

      #include <cstdio>
      #include <filesystem>
      #include <iostream>
      #include <string_view>
      namespace fs = std::filesystem;

      void explain(std::string_view note, fs::filesystem_error const& ex)
      {
	  std::cout << note << " exception:\n"
		    << "what(): " << ex.what() << '\n'
		    << "path1(): " << ex.path1() << ", path2(): "
		    << ex.path2() << "\n\n";
      }

      int main()
      {
	  try
	  {
	      std::filesystem::rename("/dev", "/null");
	  }
	  catch(fs::filesystem_error const& ex)
	  {
	      explain("fs::rename()", ex);
	  }

	  for (auto const path : {"/bool", "/bin/cat", "/bin/mouse"})
	      try
	      {
		  std::filesystem::create_directory(path);
	      }
	      catch(fs::filesystem_error const& ex)
	      {
		  explain("fs::create_directory()", ex);
	      }
      }

Possible output:
      fs::rename() exception:
      what(): filesystem error: cannot rename: Permission denied [/dev] [/null]
      path1(): "/dev", path2(): "/null"

      fs::create_directory() exception:
      what(): filesystem  error:  cannot  create  directory:  Permission  denied
     [/bool]
      path1(): "/bool", path2(): ""

      fs::create_directory() exception:
      what(): filesystem error: cannot create directory: File exists [/bin/cat]
      path1(): "/bin/cat", path2(): ""

      fs::create_directory() exception:
      what():  filesystem  error: cannot create directory: Read-only file system
     [/bin/mouse]
      path1(): "/bin/mouse", path2(): ""

http://cppreference.com 	   2024.06.10	   std::filesy..._error::what(3)
home | help