PHP预定义函数 - count - 在多维数组中返回一个奇怪的（对我来说）值？

I started learning PHP from a book and I got a list of useful PHP commands(sort, count, is_array ect.)

I tried using count() but it seems tricky to me.

count($chessboard, 0) outputs 8 and that's fine I think (because it has 8 rows, I get it) but when I use count($chessboard, 1) it outputs 72 and I don't get why.

In my opinion I think it should output 64 (because 8 rows * 8 columns or 8 rows * 8 elements per row).

Why does it output 64?

<?php
$chessboard = array(
    array('r', 'n', 'b', 'q', 'k', 'b', 'n', 'r'),
    array('p', 'p', 'p', 'p', 'p', 'p', 'p', 'p'),
    array(' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '),
    array(' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '),
    array(' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '),
    array(' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '),
    array('P', 'P', 'P', 'P', 'P', 'P', 'P', 'P'),
    array('R', 'N', 'B', 'Q', 'K', 'B', 'N', 'R')
  );
  
echo count($chessboard, 1);

</div>

When you pass 1 as the second parameter to count(), it counts recursively - so for the first level it counts 8 items (meaning 8 sub-arrays) and then proceeds to second level, where it encounters 8 items in each sub-array. Thus 8 + 8 * 8 = 72.

You have inserted multiple arrays inside an array and passed the mode '1' to count() . This makes it count recursively and it starts counting the sub arrays inside the main array which has 8 sub arrays in your case. So 8 is the number of count for the first case i.e. main array has 8 sub arrays. Then it starts counting recursively another 8 subarrays which gives u a total 64. So here, 64+8=72. Hope it helps.