I'm looking for a C++ library which parses the command line, but - doesn't know anything about what the application's command line is actually supposed to be. It therefore uses only common-convention syntax - but still has flags, (string) key-value pairs and positional parameters, at least.
Its (partial) parsing result must be readily usable by other code, so that it's convenient to use.
Desired features:
- FOSS
- Actively-maintained
- Supports multiple occurrences of the same parameter
- C++11 or later
