Check if file is open.
  The function returns true if a previous call to open succeeded and there have been no calls to member close since, meaning that the filebuf object is currently associated with a file.

Parameters.

none

 

Return Value.
  true if a file is open.
  false otherwise.

Example.

// is_open () example
#include <iostream>
#include <fstream>
using namespace std;

int main () {

  ifstream is;
  filebuf * fb;

  fb = is.rdbuf();
  fb->open ("test.txt",ios::in);

  if ( fb->is_open() )
    cout << "file is open.\n";
  else
    cout << "file is not open.\n";

  fb->close();

  return 0;
}

Basic template member declaration ( basic_filebuf<charT,traits> ):

bool is_open ( );

See also.
  close, open
  filebuf class