How can I exclude some characters from a class?

Question

Say I want to match a "word" character (\w), but exclude "_", or match a whitespace character (\s), but exclude "\t". How can I do this?

Diskson

For the benefit of others who may be using Java, .NET, XML schema, or JGSoft/RegexBuddy, there is actually a character subtraction mechanism for those flavors: #3202189 ; e.g. [a-z-[aeiou]] in .NET matches a lowercase consonant. – Screak

Answer 1

Use a negated class including \W or \S.

/[^\W_]/  # anything that's not a non-word character and not _
/[^\S\t]/ # anything that's not a non-space character and not \t

Speller

+1 I call this technique a double-negative. – Unpeople

@ThomasGuyot-Sionnest doing plus is easy; [/[:graph:]]. but / is already in graph. maybe you meant minus the / character? [^/[:^graph:]] may work for that; not sure what regex engine git is using – Speller

@ysh TBH I can't even make sense of what I wrote above - it wasn't that easy obviously but I don't exactly remember what I was struggling with. I will delete that comment. I remember I found a solution though, will have to look back at what I did... IIRC it used the cntrl class. – Kano

I finally checked... my use case was doing a git word diff where I could see just individual path component changes (to compare two build logs with slight path modification), and I'm not sure what I tried but it's very possible I wasn't even trying the right thing at first. It appears the default regex for --word-diff is [^[:space:]]+ (I see no diff using it vs plain --word-diff) and to split on paths too I just added /, so git diff '--word-diff-regex=[^[:space:]/]+' [...]. – Kano

Close, but not cigar. \W excludes characters I need included. – Adenosine

@Adenosine what do you need? I can help – Speller

@Speller problem regex. I needed it to match the last }, so I could replace that with \n},. I have since done this manually, and it was annoying. – Adenosine

@Adenosine I can't get from that what you are trying to do; you want to match balancing {} maybe? what programming language is this? – Speller

@Adenosine if you are looking for }, at the end of a line that doesn't start with {, ^\s+[^{\s].*},$ or use the possessive modifier ^\s++[^{].*},$ – Speller