W3cubDocs

/C++

std::basic_ifstream::is_open

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

#include <string>
#include <fstream>
#include <iostream>
//this file is called main.cpp
 
bool file_exists(const std::string& str)
{
   std::ifstream fs(str);
   return fs.is_open();
}
 
int main()
{
  std::boolalpha(std::cout);
  std::cout << file_exists("main.cpp")  << '\n'
            << file_exists("strange_file") << '\n';
}

Possible output:

true
false

See also

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

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/io/basic_ifstream/is_open