How to use C++ getopt_long() if I have more than 26 options?

Question

This is a rather hypothetical question, but let's say I have 3 long parameters that begin with the same letter.

--parse or -p
--prune or -r
--pivot or -i

Eventually I'll start running out of single letters that make sense, more over, it's hard assign something meaningful in GNU getopt_long() configuration.

{"parase", no_argument,       0, 'p'},
{"prune",  no_argument,       0, 'r'},
{"pivot",  required_argument, 0, 'i'}

What is the best practice in these situations?

Answer 1

You don't have to use printable characters for the val member. Moreover, it's int, not char. It should just assist you with identifying the option. (meaning, you don't have to have corresponding shorty).

Answer 2

You have a choice of uppercase, as well as lowercase, giving you 52 short options, however many programs that accept long options don't even bother assigning short options to some options, forcing the user to use the long options only, which OK.

Answer 3

The digits 0-9 can be used to. Imagine a data compression program which would either accept -compression=[0-9], or just -[0-9] (I don't know if this works with getopt, though).

Also, uppercase can be used, too.

I understand that's a hypothetical question, but with so many options, the program probably does too much or needs a configuration file.