Add a space between every 2 characters starting from the end of a string

Question

I want to add space before every two characters from the end of the string.

$str = 9010201;

The result should be 9 01 02 01.

I tried chunk_split() and str_split(), but it worked only from the beginning of the string but not from the last.

Answer 1

simple use strrev() and chunk_split()

<?php

$str = 9010201;

echo trim(strrev(chunk_split(strrev($str),2, ' ')));

?>