Array count and length in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of count() with nested arrays

What is the output of the following PHP code?

PHP

<?php
$array = [1, 2, [3, 4], 5];
echo count($array);
?>

A 3

B 5

C Error

D 4

💡 Hint

count() counts the top-level elements only.

The array has four elements: 1, 2, [3,4], and 5. The nested array counts as one element.

❓ Predict Output

intermediate

Difference between count() and sizeof()

What will this PHP code output?

PHP

<?php
$arr = ['a', 'b', 'c'];
echo count($arr) . ' ' . sizeof($arr);
?>

A 3 0

B 0 3

C 3 3

D Error

💡 Hint

sizeof() is an alias of count() in PHP.

Both count() and sizeof() return the number of elements in the array, which is 3.

❓ Predict Output

advanced

Count with COUNT_RECURSIVE flag

What is the output of this PHP code?

PHP

<?php
$array = [1, 2, [3, 4], 5];
echo count($array, COUNT_RECURSIVE);
?>

A 4

B 6

C 5

D Error

💡 Hint

COUNT_RECURSIVE counts all elements including nested arrays.

The array has 4 top-level elements, but the nested array has 2 elements, so total is 4 + 2 = 6.

❓ Predict Output

advanced

Length of string vs count() on string

What will this PHP code output?

PHP

<?php
$str = "hello";
echo count($str);
?>

A 1

B 5

C Error

D 0

💡 Hint

count() on a string returns 1 because string is not an array.

count() returns 1 when given a non-array, non-countable variable like a string.

🧠 Conceptual

expert

Why does count() return 1 on a string?

In PHP, why does count() return 1 when called on a string variable?

A Because count() treats any non-array as a single element

B Because strings are internally arrays of characters

C Because count() counts characters in the string

D Because count() throws an error on strings

💡 Hint

Think about how count() handles non-array inputs.

count() returns 1 for any scalar (non-array) value, treating it as a single element.