Iterating Over Multidimensional Arrays in PHP

Let's now learn how to iterate over multidimensional arrays using loops. Suppose we have the following array:

php<?php
  $arr = [
    ['a', 'b', 'c'],
    ['d', 'e', 'f'],
    ['g', 'h', 'i'],
  ];
?>

As you can see, this array is two-dimensional, which means that to iterate through it, two nested foreach loops are needed:

php<?php
  foreach ($arr as $sub) {
    foreach ($sub as $elem) {
      echo $elem;
    }
  }
?>

php<?php
  $arr = [[1, 2, 3], [4, 5, 6, 7], [8, 9]];
?>