Regular Expression to Match URLs with or without Protocols

For URLs that may or may not include the "http://www" prefix, a regular expression can be used to perform the matching operation. A detailed RegEx pattern is provided below:

((https?|ftp)://)?([a-z0-9 !*(),;?&amp=$_.-] (:[a-z0-9 !*(),;?&amp=$_.-] )?@)?([a-z0-9\-\.]*)\.(([a-z]{2,4})|([0-9]{1,3}\.([0-9]{1,3})\.([0-9]{1,3})))(:[0-9]{2,5})?(/([a-z0-9 $_%-]\.?) )*/?(\?[a-z &\$_.-][a-z0-9;:@&%= /$_.-]*)?(\#[a-z_.-][a-z0-9 $%_.-]*)?

To utilize this pattern for URL validation, it can be applied in the following manner:

if (preg_match("~^$regex$~i", 'www.example.com/etcetc', $m))
    var_dump($m);

if (preg_match("~^$regex$~i", 'http://www.example.com/etcetc', $m))
    var_dump($m);

This RegEx solution offers a comprehensive way to match URLs regardless of whether they contain the "http://" prefix or not.