Thread: Creating a commandline

I want to make something, kind of like the Windows commandline thing. Such as, the program will have a number of recognized commands such as 'log' or 'run'. This is for learning purposes, so I don't care if these commands exist already. How exactly do I check if the command is recognized or if the parameter after it, is valid. For example, I type 'run blah', this will not be valid. But how can this be checked? Also, how do I define the commands like 'run' or 'log'?

First, you use a tokenizer. This splits up the input line into individual strings eg. "foo bar baz" -> "foo", "bar", "baz".

Now it is trivial to see if the command is supported. The Q&D way is to just hunt for it in a list of valid commands. Or you could get fancy and use a hash.

Edit: Nevermind.

Ugh...I can see this turning into a scripting engine type setup. A tokenizer is a lexer correct?

More precisely it is a rather dumb scanner, and scanners -- especially one for your needs -- are simple to write.