How to get a substring between two strings in PHP?

Answer 1

In PHP's strpos style this will return false if the start mark sm or the end mark em are not found.

This result (false) is different from an empty string that is what you get if there is nothing between the start and end marks.

function between( $str, $sm, $em )
{
    $s = strpos( $str, $sm );
    if( $s === false ) return false;
    $s += strlen( $sm );
    $e = strpos( $str, $em, $s );
    if( $e === false ) return false;
    return substr( $str, $s, $e - $s );
}

The function will return only the first match.

It's obvious but worth mentioning that the function will first look for sm and then for em.

This implies you may not get the desired result/behaviour if em has to be searched first and then the string have to be parsed backward in search of sm.