NAME

std::basic_filebuf::is_open - std::basic_filebuf::is_open

Synopsis

bool is_open() const;

Returns true if the most recent call to open() succeeded and there has been no call
to close() since then.

Parameters

(none)

Return value

true if the associated file is open, false otherwise.

Notes

This function is typically called by std::basic_fstream::is_open().

Example

// Run this code

#include <fstream>
#include <iostream>

int main()
{
std::ifstream fs("test.txt");
std::filebuf fb;
fb.open("test.txt", std::ios_base::in);
std::cout << std::boolalpha
<< "direct call: " << fb.is_open() << '\n'
<< "through streambuf: " << fs.rdbuf()->is_open() << '\n'
<< "through fstream: " << fs.is_open() << '\n';
}

Output:

direct call: true
through streambuf: true
through fstream: true

See also

open opens a file and configures it as the associated character sequence
(public member function)
close flushes the put area buffer and closes the associated file
(public member function)