What's an effective way to parse command line parameters in C++?

Question

Is there a really effective way of dealing with command line parameters in C++?

What I'm doing below feels completely amateurish, and I can't imagine this is how command line parameters are really handled (atoi, hard-coded argc checks) in professional software.

// Command line usage: sum num1 num2

int main(int argc, char *argv[])
{
   if (argc < 3)
   {
      cout << "Usage: " << argv[0] << " num1 num2\n";
      exit(1);
   }

   int a = atoi(argv[1]);
   int b = atoi(argv[2]);
   int sum = a + b;

   cout << "Sum: " << sum << "\n";

   return 0;
}

Answer 1

You probably want to use an external library for that. There are many to chose from.

Boost has a very feature-rich (as usual) library Boost Program Options.

My personal favorite for the last few years has been TCLAP -- purely templated, hence no library or linking, automated '--help' generation and other goodies. See the simplest example from the docs.

Answer 2

You could use an already created library for this

http://www.boost.org/doc/libs/1_44_0/doc/html/program_options.html

Answer 3

if this is linux/unix then the standard one to use is gnu getopt

http://www.gnu.org/s/libc/manual/html_node/Getopt.html

Answer 4

I would recommend always using boost lexical_cast<> in place of junk like atoi, atof, etc.

http://www.boost.org/doc/libs/release/libs/conversion/lexical_cast.htm

Other than that your code okay for simple stuff.