Array count and length in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What function in PHP is used to count the number of elements in an array?

The count() function returns the number of elements in an array.

beginner

What will count([]) return in PHP?

It returns 0 because the array is empty and has no elements.

beginner

How does PHP treat the length of an array compared to the count of an array?

In PHP, the length of an array is the same as the count of its elements. Use count() to get this number.

intermediate

What is the difference between count() and sizeof() in PHP?

Both count() and sizeof() return the number of elements in an array. They are aliases and work the same way.

intermediate

What happens if you use count() on a variable that is not an array?

If the variable is not an array or an object implementing Countable, count() returns 1 if the variable is not null, otherwise 0.

What does count($arr) return if $arr = [1, 2, 3, 4]?

A 1

B 3

C 4

D Error

count() returns the number of elements, which is 4 here.

Which PHP function is an alias of count()?

A length()

B sizeof()

C array_length()

D size()

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

What will count(null) return in PHP?

A 0

B 1

C null

D Error

count(null) returns 0 because null is treated as empty.

If $arr = ['a' => 1, 'b' => 2], what does count($arr) return?

A 2

B 1

C 0

D Error

Associative arrays count their elements the same as indexed arrays.

Which of these is NOT a valid way to get the number of elements in an array in PHP?

A count($array)

B sizeof($array)

C Both A and B

D length($array)

length() is not a PHP function for arrays.

Explain how to find the number of elements in a PHP array and what happens if the variable is not an array.

Think about the function count() and what it returns for different types.

Describe the difference, if any, between the length of an array and the count of an array in PHP.

Consider how PHP measures array size.