Find the last occurence of a needle in a haystack

Question

In Textpad, is it possible to find the last occurence of a string within a string, so, for instance...

Find the last occurrence of _ within

FF_SF_FIRE_STRATEGY_G

So that you can then obtain either FF_SF_FIRE_STRATEGY or G

?

UPDATE: This solves half the problem: _[A-Z]\>

How does `_[A-Z]\>` solve the problem? `\>` doesn't appear anywhere in your example. — CAustin, Mar 01 '19 at 18:53
@caustin in textpad, I think it means the end of the string, but I may have misunderstood — Strawberry, Mar 01 '19 at 19:19
I don't use textpad, but I'd be surprised if that were the case. Can you post your full input? — CAustin, Mar 01 '19 at 19:23
Are you within a substitution process by this? Why not to use `^$.*$_$.*$$`? — revo, Mar 01 '19 at 19:31

score 0 · Accepted Answer · answered Mar 01 '19 at 18:23

0

You may use a negative lookahead based regex:

_(?!\S*_)

RegEx Demo

Here (?!\S*_) is a negative lookahead that asserts that we don't have any more _ following 0 or more non-whitespace characters on right hand side.

answered Mar 01 '19 at 18:23

anubhava

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I think TextPad's implementation of Regex is a little different – Strawberry Mar 01 '19 at 18:24
textpad allows lookahead expression, See this: https://superuser.com/questions/1251842/textpad-8-regular-expression-with-multiple-conditions/1252066#1252066 – anubhava Mar 01 '19 at 18:31
Well, it doesn't allow *this* one :-( - version 5.4.2, if it makes any difference – Strawberry Mar 01 '19 at 18:33
1

The answer appears to be to upgrade! – Strawberry Mar 01 '19 at 20:23

score 0 · Answer 2 · answered Mar 01 '19 at 19:44

According to textpad the regex syntax it used before v7 was POSIX and later it adopted Perl regular expressions. So best is to upgrade your textpad else the following regex attempts to match _ and captures its preceding / following non-whitespace characters:

\(^|[[:blank:]]\)\([^[:blank:]]*\)_\([^[:blank:]_]*\)\([[:blank:]]|$\)

It has 4 capturing groups and what you need is hold by \2 and \3.

See a Perl compatible demo here

Find the last occurence of a needle in a haystack

2 Answers2