RegEx checks the validity of input information in. net.

Use. Net's RegEx to determine the legality of the input information. Let's take a look at the following example:

RegEx. ismatch ("username", @ "[a-zA-Z0-9] [a-zA-Z0-9 _] {} [a-zA-Z0-9]")

This is to determine the validity of an input user name. The length of the user name is 2-29 characters.

True is returned if it is valid. False is returned if it is invalid.

The following regular expression is determined according to your requirements.

Reference using system. Text. regularexpressions before use;

You can also write a class. I will not give an example here.