Find and replace a specific number with regex

Question

I have the following string

string absoluteUri = "http://localhost/asdf1234?$asdf=1234&$skip=1234&skip=4321&$orderby=asdf"

In this string I would like to replace '$skip=1234' with '$skip=1244'

I have tried the following regular expression:

Regex.Replace(absoluteUri, @"$skip=\d+", "$skip=1244");

Unfortunately this is not working. What am I doing wrong?

The output should be:

"http://localhost/asdf1234?$asdf=1234&$skip=1244&skip=4321&$orderby=asdf"

user21926 · Accepted Answer · 2013-09-26 20:30:28Z

4

$ is a special character in regular expressions (it's an anchor). You need to escape it in both the expression and in the replacement string, but they are escaped differently.

In the regular expression, you escape it with a \ but in the substitution you escape it by adding another $:

Regex.Replace(absoluteUri, @"\$skip=\d+", "$$skip=1244");

answered Sep 26, 2013 at 20:30

user21926

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2 Comments

niklr Over a year ago

Great, thank you! The escaping with \ did the trick. I'm not sure why but it works with and without escaping the replacement string.

user21926 Over a year ago

Probably because $s is not a valid replacement string and it ignores it. I'd recommend using $$ in the replacement even if it is not strictly necessary in this case.

Dmitresky · Accepted Answer · 2013-09-26 20:41:27Z

0

I can't add comment. Just little fix. Need to do:

absoluteUri = Regex.Replace(absoluteUri, @"\$skip=\d+", "$skip=1244");

answered Sep 26, 2013 at 20:41

Dmitresky

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