C++ alternative to perror() - c++

Question

I know we can use
perror()
in C to print errors. I was just wondering if there is a C++ alternative to this, or whether I have to include this (and therefore stdio.h) in my program. I am trying to avoid as many C functions as possible.

Answer 1

You could do something like:
std::cerr << strerror(errno) << std::endl;
That still ends up calling strerror, so you're really just substituting one C function for another. OTOH, it does let you write via streams, instead of mixing C and C++ output, which is generally a good thing. At least AFAIK, C++ doesn't add anything to the library to act as a substitute for strerror (other than generating an std::string, I'm not sure what it would change from strerror anyway).

Answer 2

You could use the boost::system_error::error_code class.
#include <boost/system/system_error.hpp>
#include <cerrno>
#include <iostream>
void
PrintError(
const std::string& message,
int error
)
{
std::cerr << message << ": " <<
boost::system::error_code(
error,
boost::system::get_system_category()
).message()
<< std::endl;
}
int
main()
{
PrintError( "something went wrong!", EINVAL );
return 0;
}
it's a tad verbose, and somewhat overkill if you aren't already using the boost_system library.

Answer 3

With C++11, we have the <system_error> header, so you should be able to use:
std::error_code{errno, std::generic_category()}.message();
Example program:
#include <system_error>
#include <iostream>
int main() {
std::cout << std::error_code{errno, std::generic_category()}.message() << '\n';
}
This prints Success.
See also:
How to convert errno to exception using <system_error>
<system_error> categories and standard/system error codes (regarding whether to use generic_category or system_category)