Some of the regular expressions are very complex and they can take lot of time to evaluate.
For instance below is a simple regular expression.
If someone inputs a huge number as shown in the below code snippet. It will take more than a minute to resolve the expression leading to lot of load on the application. So we would like to give a time out on the expression. So if the validation takes more than a specific interval we would like the application to give up and move ahead.
In .NET 4.5 we can now provide the timeout value as parameter on the constructor. For instance in the below code we have provided 2 seconds timeout on the regex (regular expression). So if it exceeds more than 2 second “regexMatchTimeOutException” will occur.
Also see following .NET interview questions video on regular expressions & can we see some practical demonstrations: -