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Question

What is wrong with this really really simple RegEx expression?

Answer 1

+2 A:

The problem is in the .(dot), which is a wildcard, You must escape it like \..

Also, Because there is a ? at the end of URL and $ (end-of-input) is in the regexp, therefore, it does not match.

The correct regexp should be ^/default\.aspx(\?.*)?$

SHiNKiROU 2010-04-14 02:24:02

You need to add \? before the $ or it won't match. The '?' is a reserved character too (meaning zero or 1 of the previous thing) and it should also be escaped with a backslash.

James 2010-04-14 02:28:36

ooho. i wasn't tooo far off it. all those brackets stuff always get me stumped, also. can you explain what (?.*) does? i'm guessing the (?.*)? says that stuff in the brackets .. well, it's optional?

Pure.Krome 2010-04-14 03:07:37

@Pure: actually, `(?.*)` is a syntax error. It should have been `(\?.*)`: a question mark followed by zero or more of anything. The question mark at the end, as you said, makes the whole group optional.

Alan Moore 2010-04-14 03:14:47

Answer 2

+1 A:

The $ at the end of ^/default.aspx$ means 'match the end of the string', but the string you're searching ends with '?'.

pzr 2010-04-14 02:25:45

Answer 3

+1 A:

Maybe something like this is more appropriate:

^/default\.aspx(\?.*)?$

This will match default.aspx, with an optional ?whatever-else-that-comes-after.

polygenelubricants 2010-04-14 02:26:20

Is there any reason to keep the $ at the end of the regex if you are doing something like ".*"?

Iuvat 2010-04-14 02:29:14

It depends on the regex implementation because typically '.' does not match new lines.

James 2010-04-14 02:31:31

That would explain what I've been missing. I'm usually only matching in single lines.

Iuvat 2010-04-14 02:32:26

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What is wrong with this really really simple RegEx expression?

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