How to extract substring by start-index and end-index?

Question

$str = \'HelloWorld\';
$sub = substr($str, 3, 5);
echo $sub; // prints \"loWor\"

I know that substr() takes the first parameter, 2nd parameter is start

Answer 1

function my_substr_function($str, $start, $end)
{
  return substr($str, $start, $end - $start);
}

If you need to have it multibyte safe (i.e. for chinese characters, ...) use the mb_substr function:

function my_substr_function($str, $start, $end)
{
  return mb_substr($str, $start, $end - $start);
}