ifstream: how to tell if specified file doesn't exist

Question

I want to open a file for reading. However, in the context of this program, it's OK if the file doesn't exist, I just move on. I want to be able to identify when the error is "file not found" and when the error is otherwise. Otherwise means I need to quit and error.

I don't see an obvious way to do this with fstream.

I can do this with C's open() and perror(). I presumed that there was a fstream way to do this as well.

user_1633272 · Answer

A better way:

std::ifstream stream;
stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
stream.open(fileName, std::ios::binary);

user_6329006 · Answer

Let's me give example with real running:

file does't exist:

file exist:

see http://www.cplusplus.com/reference/fstream/ifstream/ for more information about its public function.

user_2588499 · Answer

Straight way without creating ifstream object.

if (!std::ifstream(filename))
{
     // error! file doesn't exist.
}

ifstream: how to tell if specified file doesn't exist

8 Answers