C# Trouble with Regex.Replace

Question

Been scratching my head all day about this one!

Ok, so I have a string which contains the following:

?\"width=\"1\"height=\"1\"border=\"0\"style=\"display:none;\">');

I want to convert that string to the following:

?\"width=1height=1border=0style=\"display:none;\">');

I could theoretically just do a String.Replace on "\"1\"" etc. But this isn't really a viable option as the string could theoretically have any number within the expression.

I also thought about removing the string "\"", however there are other occurrences of this which I don't want to be replaced.

I have been attempting to use the Regex.Replace method as I believe this exists to solve problems along my lines. Here's what I've got:

chunkContents = Regex.Replace(chunkContents, "\".\"", ".");

Now that really messes things up (It replaces the correct elements, but with a full stop), but I think you can see what I am attempting to do with it. I am also worrying that this will only work for single numbers (\"1\" rather than \"11\").. So that led me into thinking about using the "*" or "+" expression rather than ".", however I foresaw the problem of this picking up all of the text inbetween the desired characters (which are dotted all over the place) whereas I obviously only want to replace the ones with numeric characters in between them.

Hope I've explained that clearly enough, will be happy to provide any extra info if needed :)

You only want to replace the \ from the width element and the border element and the style element? — woutervs
– woutervs, Commented Nov 29, 2013 at 12:33

Jonas Elfström · Accepted Answer · 2013-11-29 12:33:01Z

3

Try this

var str = "?\"width=\"1\"height=\"1234\"border=\"0\"style=\"display:none;\">');";
str = Regex.Replace(str , "\"(\\d+)\"", "$1");

(\\d+) is a capturing group that looks for one or more digits and $1 references what the group captured.

answered Nov 29, 2013 at 12:33

Jonas Elfström

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Stewart Whitworth Over a year ago

Ah nice one mate, I now understand I should have been looking for backreferences. Works perfectly.

David S. · Accepted Answer · 2013-11-29 12:37:30Z

1

This works

String input = @"?\""width=\""1\""height=\""1\""border=\""0\""style=\""display:none;\"">');";

//replace the entire match of the regex with only what's captured (the number)
String result = Regex.Replace(input, @"\\""(\d+)\\""", match => match.Result("$1"));

//control string for excpected result
String shouldBe = @"?\""width=1height=1border=0style=\""display:none;\"">');";

//prints true
Console.WriteLine(result.Equals(shouldBe).ToString());

answered Nov 29, 2013 at 12:37

David S.

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