I want to write regex that starts and end with numbers and letters only but can have special charact-CodePudding

I tried writing this: ^[A-Za-z0-9-][A-Za-z0-9- ]{1,30}$ But the regex should not start and end with a special character or space.

Sample values It should allow:

EcoLight

Eco-Light

Eco_Light

Eco Light

Eco Light 1

CodePudding user response：

One option would be to use:

^(?!.{31})[A-Za-z0-9] (?:[ _-][A-Za-z0-9] )*$

See an online demo. The negative lookahead will prevent over 30 characters while the non-capture group allows for multiple groups of characters that are delimited through any of the characters in the class [ _-].

CodePudding user response：

If the regex pattern ends with a letter or digit then it won't end with something else

^[A-Za-z0-9-][A-Za-z0-9_ -]{0,29}[A-Za-z0-9]$