PHP var security

PHPsec

Looking for functions to clean vars for different situations.

Can you improve on these, returning strings, urls and numbers:

function strClean($var) {
	// returns converted entities where there are HTML entity equivalents
	return htmlentities($var, ENT_QUOTES, "UTF-8");
}

function urlClean($var) {
	// returns a-z A-Z 0-9 / - . _ chars only
	return preg_replace('/[^a-zA-Z0-9\/\-\._]/si','',$var);  
}

function numClean($var) {
	// returns a number, whole or decimal or null
	return is_numeric($var) ? floatval($var) : false;
}

@maettig Thanks. Used that as a better solution to my $var*1 === $var ? $var : false; effort. Will use look at parse_url to get the various elems and then sanitise the values as @jedisct1 suggested.