Question Regex parsing "^[a-zA-Z0-9]{5,20}+$" - Nested quantifier +

Hi,
I'm trying to use regex:

if (!Regex.Match(name, "^[a-zA-Z0-9]{5,20}+$").Success)

However, it gives error:

ArgumentException: parsing "^[a-zA-Z0-9]{5,20}+$" - Nested quantifier +.

When trying to escape +:

if (!Regex.Match(name, "^[a-zA-Z0-9]{5,20}//+$").Success)

it is not working - no error, but every string is invalid.

Please help.

 

You need to surround the expression you want to use the

+

symbol on with parentheses like this:

^([a-zA-Z0-9]{5,20})+$

Here's a version of it modified to look for whitespace in case you're trying to support multiple words:

^([a-zA-Z0-9]{5,20}[\s]{0,1})+$

For debugging regular expressions I recommend the following site:

https://regex101.com/

 

Thank you very much!