JuniorTheoryCommon

What does the program print?

PHP

<?php

$a = [];
$a['8'] = 'x';
$a[8] = 'y';
$a['08'] = 'z';
$a[] = 'w';
echo count($a), ' ', implode(' ', array_keys($a)), "\n";

3 8 08 9

Expecting '8' and 8 to be two separate keys: a string holding a plain decimal integer is cast to int, so $a[8] = 'y' overwrites the value under '8'.
Expecting $a[] to add the element at index count($a): the next index is the largest integer key plus one, here 9, however many elements there are.

JuniorTheoryCommon

PHP

<?php

$a = [];
$a['8'] = 'x';
$a[8] = 'y';
$a['08'] = 'z';
$a[] = 'w';
echo count($a), ' ', implode(' ', array_keys($a)), "\n";

3 8 08 9

Expecting '8' and 8 to be two separate keys: a string holding a plain decimal integer is cast to int, so $a[8] = 'y' overwrites the value under '8'.
Expecting $a[] to add the element at index count($a): the next index is the largest integer key plus one, here 9, however many elements there are.