std::basic_fstream<CharT,Traits>::is_open - cppreference.com (original) (raw)

Checks if the file stream has an associated file.

Effectively calls rdbuf()->is_open().

[edit] Parameters

(none)

[edit] Return value

true if the file stream has an associated file, false otherwise.

[edit] Example

#include #include #include   int main() { std::string filename = "some_file";   std::fstream fs(filename, std::ios::in);   std::cout << std::boolalpha; std::cout << "fs.is_open() = " << fs.is_open() << '\n';   if (!fs.is_open()) { fs.clear(); fs.open(filename, std::ios::out); std::cout << "fs.is_open() = " << fs.is_open() << '\n'; } }

Possible output:

fs.is_open() = false fs.is_open() = true

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also

| | opens a file and associates it with the stream (public member function) [edit] | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | closes the associated file (public member function) [edit] |