Regular Expression for URL

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JJ - 01 Jun 2007 15:21 GMT

I can get a set of matches of URL's by using a match expression that has a
named capture group in it, i.e.:

Regex reg_linkTags = new Regex("(?:.....long resular
expression......)(?<url>\\w+|\"[^\"]*\"|'[^']*')(?:(?:\\s+\\w+\\s*=\\s*)(?:
.....long regular expression......)", RegexOptions.IgnoreCase |
RegexOptions.Compiled | RegexOptions.Multiline);
MatchCollection tagMatches = reg_linkTags.Matches(myString);

Then get the url named capture group by:
for (int i = 0; i <= (tagMatches.Count - 1); i++)
{

CurrentUrl = tagMatches[i].Result("${url}");

BUT how do I _replace_ the url in the original string ('myString'). I can
match them , but I cannot seem to replace them. I tried using regex.replace,
but I don't think I can use this with either 'non capturing groups' (which I
wrap the named capture group 'url' in) or with named capture groups can I?

Thanks,
JJ

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Alexey Smirnov - 01 Jun 2007 20:03 GMT

> I can get a set of matches of URL's by using a match expression that has a
> named capture group in it, i.e.:
[quoted text clipped - 10 lines]
>
> CurrentUrl = tagMatches[i].Result("${url}");

What about simple replace?

CurrentUrl = tagMatches[i].Result("${url}");
myString = myString.replace(CurrentUrl, newUrl);

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JJ - 04 Jun 2007 18:16 GMT

> What about simple replace?
>
> CurrentUrl = tagMatches[i].Result("${url}");
> myString = myString.replace(CurrentUrl, newUrl);

Ah thats what I did in the first place. However, when the href and the src
parts of the tag had identical beginning sections, both were replaced - in
my case I didn't want that to happen.

What I ended up doing was creating another reg expression to pull out just
the href url so that I could replace it. Just thought there may be any
easier way to use named capture groups to replace (not just capture) text.
Maybe there is, but as yet I've not a clue how to do it.

Thanks,

JJ

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Alexey Smirnov - 04 Jun 2007 20:45 GMT

> > What about simple replace?
>
[quoted text clipped - 13 lines]
>
> JJ

I think there is one more possibility

Change your pattern to return all content in a groups

(?<textbefore>...)(?<url>...)(?<textafter>...)

In this case you could use the following replacement statement

string newUrl = "http://.......";
string result = reg_linkTags.Replace(text, "${textbefore}" + newUrl +
"${textafter}");

You can also use a MatchEvaluator delegate to custom string function
that can be called at each match to evaluate the replacement value.

string result = reg_linkTags.Replace(text, new
MatchEvaluator(NewUrl));

string NewUrl(Match m)
{
string x = m.Groups["Domain"].ToString();
...
return "something";
}

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JJ - 05 Jun 2007 18:01 GMT

I didn't think of that. Thanks,

JJ

>> > What about simple replace?
>>
[quoted text clipped - 42 lines]
> return "something";
> }

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Regular Expression for URL

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