Trying to use regex to parse arguments from a string: "-a 1 -b -5.1".
Output should have 2 flags with values: flag a with value 1, b with -5.1.
When I try (-(?<flag>[a-zA-Z])(?<value> .+)?(?!-[a-zA-Z]))* regular expression, it returns only flag a with value 1 -b -5.1.
Why doesn't it stop at -b?
You need to make (?<value> .+) lazy and turn the negative lookahead into a positive lookahead.
Here is my try:
-(?<flag>[a-zA-Z]) (?<value>.+?)(?=$| -[a-zA-Z])
Explanation:
You are probably wondering why a positive lookahead is used instead of a negative one. This is because +? will stop matching whenever the thing after it matches. This is why we look ahead to find $| -[a-zA-Z] and if we do find one, +? stops matching!
I have also moved a space character outside of the value group. I assume you don't want the value to contain spaces?