I want to match two separate patterns. I can get the first working but not the second.
The first is that one of [eE] must be immediately preceded by one of [cfd] but one or more of G is optionally allowed between them. For example, the expression [cfd]G*[eE] works on this text as I would expect:
cexmxcGexcexGGG0cexG0G00cGEgx0xgcex0xcGGGGEgx0xgmcexc
The second pattern I want to match is any occurrence of [eE] preceded by [^cfd] even if there are zero, one or more of G between them. I think something like [^cfd]G*[eE] should work on a slightly modified text:
cexmxcGexcexGGG0vexG0G00cGEgx0xgcex0xvGGGGEgx0xgmcexc. I would only expect the ve and vGGGGE strings to be matched. However, I am getting the two other G[eE] patterns matched as well even though they are part of a valid cG*e matched by the first pattern [cfd]G*[eE].
How do I avoid matching the G[eE] substrings in the second example and why is this happening?
CodePudding user response：
If you only want to match ve and vGGGGE you can exclude matching G om the negated character class as well.
What happens is that [^cfd] can also match a G char.
So [^cfd]G*[eE] can match G, then G* match optional G chars, and then matches e or E which can also match Ge and GE
[^cfdG]G*[eE]