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

From cppreference.com
< cpp‎ | io‎ | basic ifstream

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

### See also

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

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