in reply to Re^3: regular expression to check if the textbox contains only special characters
in thread regular expression to check if the textbox contains only special characters

Hi choroba

Understood this and solved the situation for me.

 print /^(?:[A-Z_]+,?)+(?<!,)$/ ? 'good' : 'bad';

should be modified as

 print /^(?:[A-Z_0-9]+,?)+(?<!,)$/ ? 'good' : 'bad';

Lookahead and Lookbehind concepts is intresting. Thank you very much.