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 index, while 3rd parameter is substring length to extract. What I need is to extract substring by startIndex and endIndex. What I need is something like this:

$str = 'HelloWorld'; $sub = my_substr_function($str, 3, 5); echo $sub; // prints "lo" 

Is there a function that does that in php? Or can you help me with a workaround solution, please?

Answer 1

It's just math

$sub = substr($str, 3, 5 - 3); 

The length is the end minus the start.

Answer 2

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); }