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

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

int main () {

  ifstream infile;
  infile.open ("test.txt");
  if (infile.is_open())
  {
    while (infile.good())
      cout << (char) infile.get();
    infile.close();
  }
  else
  {
    cout << "Error opening file";
  }
  return 0;
}

This example uses is_open to check whether the file has successfully been opened, if so prints out the content of the file, otherwise -like for example if the file to be opened doesn't exist- an error message is shown.

Basic template member declaration

bool is_open ();

See also