What is the C++ stream equivalent to perror? [duplicate]

Question

Possible Duplicate:
C++ alternative to perror()

I can't find the stream equivalent to perror. Is there such a thing? I like the fact that I can call:

perror("Error");

And it will fill in what errno is. Can I do this with streams?

Answer 1

To print an error message:

str << strerror(errno);

If you're talking about the streams error state - no you can't get an automatic meaningful error message for that.

Answer 2

Since perror writes to stderr, any equivalent in C++ has to do exactly the same. That is, it is not sufficient to write strerror(errno) to a stream. The stream itself should (I'd say must) be a stream to standard error.

The following code snippet/pseudo code should give you an idea:

// depending on your compiler, this is all you need to include
#include <iostream>
#include <string.h>
#include <errno.h>

 ... somewhere in your code...

std::cerr << "Error: " << strerror(errno) << std::endl;