slug/permalink validation

gistfile1.php

<?php

// lower alpha

// alnum followed by alnum or hyphen between alnum
function valid_slug1($value)
{
	return (bool) preg_match('/^[a-z0-9]+(-[a-z0-9]+)*$/iD', (string) $value);
}

// alpha followed by alnum or hyphen between alnum
function valid_slug2($value)
{
	return (bool) preg_match('/^[a-z]+(-?[a-z0-9]+)*$/iD', (string) $value);
}