Question

I am fairly new into regexes, so I wrote the following simple regex using positive lookahead that detects functions and function calls in a C source file-

\w+(?=\s*\()

It works fine, but the problem is it detects non-function syntaxes like if(), while()etc too.
I can easily avoid this by saying-

(if(?!\()) | (while(?!\())

But the problem is how to combine the second regex with the first one? I cant OR them, cos the first one still matches if(), while() etc and in an OR expression, its enough if one of the term matches.

How to combine these regexes or have a better simpler one which will not match non-function syntaxes like if(), while()

PS: I use the following tools to test my regexes

GSkinner

RegexPal

Answer 1

There are quite a lot of assumptions when you are searching for function call in C with regex. That aside, if you are happy with what is matched (there are valid function calls that will not be matched), and you want to exclude if and while from the result list, you can use the following regex:

(?!\b(if|while|for)\b)\b\w+(?=\s*\()

The regex uses word boundary \b to make sure that the whole name is matched (prevent partial matching of hile in while), and the whole name is not keyword (prevent rejection of whilenothinghappens).