C# regex to match a string which has a delimiter

Question

I want to get the string which has a delimiter in it, between two specific words, using a regex.

e.g. I need a regex which matches:

Statements1 start Statements2 ; Statements3 end fun;

There can be multiple occurrences of ' ; ' between 'start' and 'end'.

Statements are multiple words where (.*) can be used in the regex for a word.

But the regex should not match if there is no ' ; ' between the 'start' and 'end'.

Also, the 'end' should be the first 'end' encountered after 'start'

So, the regex should not match

Statements1 start Statements2 end Statements3 ; end fun

I want the matches as

statements before 'start'
keyword
statements after 'start'

So, in this case it would be a group(for the 1st string since 2nd should not match) as:

Statements1
start
Statements2 ; Statements3 end fun;

Gavin Miller · Accepted Answer · 2009-03-13 13:34:35Z

1

So the below regex will match your positive case and fail the negative case and place the results into group 1, 2, & 3.

(.*?) (start) ((?:(?:.*?) ;)+ (?:.*?) end fun)

In case you're unfamiliar with the (?:) syntax - they signify non-capturing parentheses. Check out Mastering Regular Expressions, it's a great reference for this topic!

answered Mar 13, 2009 at 13:34

Gavin Miller

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1 Comment

Archie Over a year ago

yes, i'm familier with the ?: syntax. But i'm sorry to say that this regex is not working.

leppie · Accepted Answer · 2009-03-13 13:10:07Z

0

start ((Statements) ;)+ (Statements) end fun

answered Mar 13, 2009 at 13:10

leppie

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2 Comments

Gavin Miller Over a year ago

This doesn't meet the capturing requirements

Gavin Miller Over a year ago

A pain when that happens isn't it!

Lazarus · Accepted Answer · 2009-03-13 13:16:47Z

0

Might be quicker to use

    string[] Strings = stringToSplit.Split(new char[] { ';' });
    if (Strings.Count() > 1)
    {
        // Do your stuff
    }

answered Mar 13, 2009 at 13:16

Lazarus

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Comments

P Daddy · Accepted Answer · 2009-03-13 13:29:17Z

0

It sounds like what you want is as simple as:

(.*)(start)(.*;.*end.*)

This would return the groups you list.

answered Mar 13, 2009 at 13:29

P Daddy

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2 Comments

Jesse Rusak Over a year ago

You need non-greedy qualifiers on your *'s, or it will match the last "end", not the first.

P Daddy Over a year ago

You're absolutely correct, although substituting lazy *s causes it to group the final "fun;" with the next match. Not sure how much this matters.

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