[RESOLVED] Regex question

[dlscott56]

I was trying to write a regular expression to look for the following conditions and am having trouble understanding how to do it. It's for reading an INI file. I know there is code out there to do this but would like to understand how to do it myself.

Here are the conditions for one line read from a text file:

1. contains one and only one '[' AND one and only one ']'
2. returns the data between the brackets
3. provides some information that allows me to trap an error if it's not a properly formatted section heading. ([[text], text], etc)

Here's what I was trying to use "\[\(.*\)\]" with regex.matches.

[stlaural]

"\[\(.*\)\]" this would return anything that is between "[" and "]" AND between parenthesis as you escaped the parenthesis with the backslash character.

"\[(.*)\]" This would return anything that is between "[" and "]" without mandatory parenthesis.

does that help ? I'm not sure I completely understand what you want tho.

[dlscott56]

Actually that's returning the brackets as well. I'd like the data between them. I'd also like to find out if there are multiple brackets "[[text]" or single brackets "[text".

Mostly I'm doing this to try and learn more about regular expressions which I've avoided doing for a long time now.

[stlaural]

(?<=\[).*(?=\](?!\]))

This regular expression is using Positive Look Behind and Positive Look Ahead AND Negative Look Ahead. Basically it catches anything that follows the first occurrence found of a "[" and that precedes the last occurrence found of a "]" so if you run it against "[text]" it will return "text", if you run it against "[[text]" it will return "[text" and if you run it against "[text]]" it will return "text]".

It works well as long as the brackets are all together like "[[[" and "]]]"

So you could split a little bit like this for a better understanding

(?<=\[) This part says "preceded by an opening bracket"
.* This one simply sais "catch anything"
(?=\](?!\])) This one is the tricky one it says "followed by a closing bracket which is NOT followed by a closing bracket

there are a couple of links in my signature to get you started. There's also this site I like to use to test out my Regular Expressions

[dlscott56]

Thanks Alex. I also am reading the links in your signature. Very helpful, I should have looked there first.

Appreciate the help and the explanation of what the expression characters are doing.