How to check for special characters using regex

Question

NET. I have created a regex validator to check for special characters means I donot want any special characters in username. The following is the code

Regex         


        

Answer 1

There's a few things wrong with your expression. First you don't have the start string character ^ and end string character $ at the beginning and end of your expression meaning that it only has to find a match somewhere within your string.

Second, you're only looking for one character currently. To force a match of all the characters you'll need to use * Here's what it should be:

Regex objAlphaPattern = new Regex(@"^[a-zA-Z0-9_@.-]*$");
bool sts = objAlphaPattern.IsMatch(username);

Answer 2

Change your regex to ^[a-zA-Z0-9_@.-]+$. Here ^ denotes the beginning of a string, $ is the end of the string.

Answer 3

Your pattern checks only if the given string contains any "non-special" character; it does not exclude the unwanted characters. You want to change two things; make it check that the whole string contains only allowed characters, and also make it check for more than one character:

^[a-zA-Z0-9_@.-]+$

Added ^ before the pattern to make it start matching at the beginning of the string. Also added +$ after, + to ensure that there is at least one character in the string, and $ to make sure that the string is matched to the end.