How to Get Array Length in PHP Using count() and sizeof()

PHP provides two built‑in functions, count and sizeof, to obtain the number of elements in a one‑dimensional array. Both functions return the same result because sizeof is simply an alias of count.

Basic usage examples:

$arr = array('0','1','2','3','4');
echo count($arr); // outputs 5

$arr = array('A','B','C');
echo sizeof($arr); // outputs 3

Both functions also work with empty arrays or undefined variables, returning 0 in those cases.

When dealing with multi‑dimensional arrays, the count function accepts a second parameter to control recursion: COUNT_NORMAL (or 0) – counts only the top‑level elements. COUNT_RECURSIVE (or 1) – counts elements in nested arrays as well.

Example of a two‑dimensional array and counting its elements:

<?php
$arr = array(
    0 => array('title' => 'News1', 'viewnum' => 123, 'content' => 'ZAQXSWedcrfv'),
    1 => array('title' => 'News2', 'viewnum' => 99,  'content' => 'QWERTYUIOPZXCVBNM')
);
?>

Counting only the top‑level entries (the two news items):

echo 'Not counting sub‑arrays: ' . count($arr, COUNT_NORMAL); // outputs 2

Counting all elements recursively:

echo 'Counting sub‑arrays: ' . count($arr, COUNT_RECURSIVE); // outputs 8

These examples demonstrate how to choose the appropriate function and parameter based on whether you need to include nested array elements in the count.

In summary, count() and sizeof() provide flexible ways to obtain array lengths in PHP, with optional recursion for multi‑dimensional structures.