Validate no spaces or Invalid Charaters

[cozzy1984]

Hi,been looking around for code that will validate that a variable entered into a form for a username contains no spaces or invalid characters and haven't had much luck. Have looked a bit at ereg and preg_match but can't seem get it working. Any ideas?

[kbluhm]

Which characters do you consider invalid?

This will check for any characters other than letters, numbers, and underscores.

if ( preg_match( '/\W/', $string ) )
{
exit( 'Bad username.' );
}


Also have a look at the character type (http://www.php.net/ctype) functions.

[cozzy1984]

cheers