[Resolved] illegal characters

[djdaz]

Hi
I am currently making a user registration form for my website and i want to restrict the available characters that users can have in there username to all letters, all numbers and the underscore(_). The problem i am having is that i dont know how to do this.

Any help would be appreciated.

Thanks

[LordShryku]

[man]preg_match[/man] or [man]ereg_match[/man]. Been discussed quite a few times here, so just search the forums for it.

[djdaz]

I found something on the forums and tried it. Now no matter what i enter i get the illegal characters found message. My code is below.

	if( !preg_match('/^[A-Za-z0-9]$/',$username) )
	{
		$page_header;
		include('nav.php');
		echo "<center><b>Your username contains invalid characters.<br><a href=\"#\" onclick=\"javascript:history.go(-1)\">Back to registration form</a></b></center>";
		include('footer.php');
		exit();
	}

[laserlight]

Basically, you're trying to write a pattern that checks that from the first to the last character, all are valid.
So you need to include the underscore, and you need to state the number of characters, i.e. 1 or more.
The pattern would then be:
/^{[A-Za-z0-9_]+$/}

[djdaz]

works perfectly now, thanks 😃