bool is_open ( );

Check if a file is open

Returns true if the stream is currently associated with a file, and false otherwise.

To determine this, the function calls: rdbuf()->is_open()

The stream is associated with a file if either a previous call to member open succeeded or if the object was successfully constructed using the parameterized constructor, and close has not been called since.

Parameters

Return Value

Example

// fstream::is_open
#include <iostream>
#include <fstream>
using namespace std;

int main () {

  fstream filestr;
  filestr.open ("test.txt");
  if (filestr.is_open())
  {
    cout << "File successfully open";
    filestr.close();
  }
  else
  {
    cout << "Error opening file";
  }
  return 0;
}

This example uses is_open to check whether the file has successfully been opened; If so, it writes a sentence to the file, otherwise it prints out an error message.

Basic template member declaration

bool is_open ();

See also