Using Regex in C# for ip:port format

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Hi all,

I am using C#.Net 2008.

I am using following code to varify proper format (udp ip:port i.e "225.1.1.1:3000") of input string.
But it is not working properly.

System.Text.RegularExpressions.Regex regStr = new System.Text.RegularExpressions.Regex(@"\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}:\d{1,5}");

bool b;
b = regStr.IsMatch("225.1.1.1:3000"); //return true
b = regStr.IsMatch("2225.1.1.1:3000"); //return true. should return false

Anybody knows proper regular expression for ip:port format?
Can anyone give me good links for using Regex , regular expression in C#.

Thanks in advance.

Regards,
Aniket A. Salunkhe

Posted 2-Dec-08 2:20am

Andy Rama

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Mirko1980 · Answer 1 · 2008-12-02T02:36:00

Solution 1

This behavior is correct, because the regexp you wrote checks for matches contained in the input string.
If you want to match the whole string only, you must add ^ at the begin and $ at the end of your regex.

For Example: "^\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}:\d{1,5}$"

Posted 2-Dec-08 2:36am

Mirko1980

la01 · Answer 2 · 2010-11-15T14:51:00

Though this is quite an old post, I thought it'll be worthwhile to add the following for future reference:

Both above regex patterns will also return true for
225*1*1*1:3000 or
225a1b1c1:3000 etc. This is because you're not using the literal "." in your pattern. Therefore, escaping the "."s in the above pattern would be a good idea, like so:

@"^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}:\d{1,5}$"

so that the literal "." character is not confused with the "." metacharacter for regular expressions.