i'm not really good at regex but i'm trying hard.... i want to validate the user's input on username, the code should only accept alphanumeric characters without whitepsaces, please check my code below if it is correct 
if(!($FORM{'username'} =~ /[^a-zA-Z0-9_]/)) {

   print "Content-type: text/html\n\n";
   print "<b> Error: spaces not allowed</b>\n";
   exit;

} else { &proceed; }

[download]
comments please, thank you.

In reply to form validation by damian

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