Question

I have a fairly long string that contains sub strings with the following format:

project[1]/someword[1]
project[1]/someotherword[1]

There will be about 10 or so instances of this pattern in the string.

What I want to do is to be able to replace the second integer in square brackets with a different one. So the string would look like this for instance:

project[1]/someword[2]
project[1]/someotherword[2]

I”m thinking that regular expressions are what I need here. I came up with the regex:

project\[1\]/.*\[([0-9])\]

Which should capture the group [0-9] so I can replace it with something else. I’m looking at MSDN Regex.Replace() but I’m not seeing how to replace part of a string that is captured with a value of your choosing. Any advice on how to accomplish this would be appreciated. Thanks much.

*Edit: * After working with @Tharwen some I have changed my approach a bit. Here is the new code I am working with:

  String yourString = String yourString = @"<element w:xpath=""/project[1]/someword[1]""/> <anothernode></anothernode> <another element w:xpath=""/project[1]/someotherword[1]""/>";
 int yourNumber = 2;
 string anotherString = string.Empty;
 anotherString = Regex.Replace(yourString, @"(?<=project\[1\]/.*\[)\d(?=\]"")", yourNumber.ToString());

Answer 1

I’ve adapted yours to use a lookbehind and lookahead to only match a digit which is preceded by ‘project[1]/xxxxx[‘ and followed by ‘]’:

(?<=project\[1\]/.*\[)\d(?=\]")

Then, you can use:

String yourString = "project[1]/someword[1]";
int yourNumber = 2;
yourString = Regex.Replace(yourString, @"(?<=project\[1\]/.*\[)\d(?=\]"")", yourNumber.ToString());

I think maybe you were confused because Regex.Replace has lots of overloads which do slightly different things. I’ve used this one.