Question

I’m trying to parse a line with negative lookahead but I’m having trouble understanding it.

So, if I have a line such as int a = sincos(a, &a);

How can I use regex to parse the line above such that it matches all the a except the one with &?

thanks.

Answer 1

I think you are actually interested in negative lookbehind here. You want instances of a that are not preceded by &.

\b(?<!&)a\b

This pattern looks for instances of a that are separated by word boundaries \b and are not immediately preceded by an ampersand (?<!&).

Including the word boundaries prevents matching a in the middle of other words, otherwise you’d have 5 matches in something like this:

var a = calculate(a, &a);