I have a problem. I'd like to match all occurrences of \t in my text (and by \t i mean it literally it is not a tab character) but I would like to exclude a match if it is a part of \t string. How to do that?
Example
<HTML>Blah</HTML>\t
D:\\UserData\\tui
I'd like to match \t in the first line but not in second line (as it is a part of \\t).
Is this at all possible using regular expressions?
You have to define more precisely what you mean by "part of a string". For example, you might mean: Don't match \t if it is followed by more alphanumerics or slash. So that would become (in Perl):
\\t(?![\w\\])
You're going to need to define in exactly which cases a \t should match, and in which ones it shouldn't, before it's possible to determine a regex for it. Your current definition seems to be of the "I'll know it when I see it" variety, which is not sufficient.
/\\t\b/
\b matches a word boundary (transition from word-like character to non-word-like, or vice versa).
Another approach: Match anything but a backslash, match a backslash and match a "t" character.
/[^\\](\\t)/