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

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

NAME

std::basic_ifstream<CharT,Traits>::is_open - std::basic_ifstream<CharT,Traits>::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>
  //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