username validity check

[pouncer]

Currently I have this:

[code=php:0]
function IsValidUsername($Username) {
if ($Username && strlen($Username) > 3) return true;
else return false;
}
[/code]

How can i expand to make sure the characters entered are characters a-z or A-Z or 0-9 ?

[steelmanronald06]

That would be regular expressions.    Of course in this instance if you just did

stripslashes
htmleneties

you would pretty much be in the clear.  Regex is mainly for email validation and things that must be string specific

[trq]

[code=php:0]
if ( preg_match('/^[a-zA-Z0-9_]{3,}$/', $Username )) return true;
[/code]

[pouncer]

Woah, thanks thorpe.