PHP – parse a string between two strings

function get_string_between($string, $start, $end){
$string = " ".$string;
$ini = strpos($string,$start);
if ($ini == 0) return "";
$ini += strlen($start);
$len = strpos($string,$end,$ini) - $ini;
return substr($string,$ini,$len);
}

$fullstring = "this is my [tag]dog[/tag]";
$parsed = get_string_between($fullstring, "[tag]", "[/tag]");

echo $parsed; // (result = dog)