NAME

std::basic_fstream::is_open - std::basic_fstream::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

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