tclap

TCLAP is a small, flexible library that provides a simple interface for defining and accessing command line arguments. It was intially inspired by the user friendly CLAP libary. The difference is that this library is templatized, so the argument class is type independent. Type independence avoids identical-except-for-type objects, such as IntArg, FloatArg, and StringArg. While the library is not strictly compliant with the GNU or POSIX standards, it is close.