std::basic_fstream<CharT,Traits>::is_open (3) - Linux Man Pages

std::basic_fstream<CharT,Traits>::is_open: std::basic_fstream<CharT,Traits>::is_open

NAME

std::basic_fstream<CharT,Traits>::is_open - std::basic_fstream<CharT,Traits>::is_open

Synopsis


bool is_open(); (until C++11)
bool is_open() const; (since C++11)


Checks if the file stream has an associated file.
Effectively calls rdbuf()->is_open().

Parameters


(none)

Return value


true if the file stream has an associated file, false otherwise

Example


// Run this code


  #include <string>
  #include <fstream>
  #include <iostream>


  int main()
  {
      std::string filename = "some_file";


      std::fstream fs(filename, std::ios::in);


      std::cout << std::boolalpha;
      std::cout << "fs.is_open() = " << fs.is_open() << '\n';


      if(!fs.is_open())
      {
         fs.clear();
         fs.open(filename, std::ios::out);
         std::cout << "fs.is_open() = " << fs.is_open() << '\n';
      }
  }

Possible output:


  fs.is_open() = false
  fs.is_open() = true

See also


      opens a file and associates it with the stream
open (public member function)
      closes the associated file
close (public member function)