function string_between($string, $start, $end,$doClean=1){
    $start="\\".$start;
    $end="\\".$end;
preg_match( "/$start(.*)$end/U", $string, $match );
if($doClean==1)
    {
    return stripslashes(htmlspecialchars($match[1]));
    }
else
    {
    return $match[1];
    }
}

// Misal
$string='Salam <span>Samir</span>, necəsən?';
$foo=string_between($string,'<span>','</span>',0);
echo $foo; // Samir