std::basic_filebuf<CharT,Traits>::is_open (3) - Linux Manuals

std::basic_filebuf<CharT,Traits>::is_open: std::basic_filebuf<CharT,Traits>::is_open

NAME

std::basic_filebuf<CharT,Traits>::is_open - std::basic_filebuf<CharT,Traits>::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