Array slice and splice in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this PHP array_slice example?

Consider the following PHP code. What will be the output when it runs?

PHP

<?php
$array = [10, 20, 30, 40, 50];
$result = array_slice($array, 2, 2);
print_r($result);
?>

A Array\n(\n [0] => 30\n [1] => 40\n)

B Array\n(\n [2] => 30\n [3] => 40\n)

C Array\n(\n [0] => 20\n [1] => 30\n)

D Array\n(\n [0] => 40\n [1] => 50\n)

💡 Hint

array_slice reindexes keys by default unless you specify the fourth parameter as true.

array_slice returns a portion of the array starting at index 2 (third element) and takes 2 elements. By default, keys are reindexed starting at 0.

❓ Predict Output

intermediate

What does this PHP array_splice code output?

Look at this PHP code snippet. What will be printed?

PHP

<?php
$array = [1, 2, 3, 4, 5];
$removed = array_splice($array, 1, 3, [9, 8]);
print_r($array);
print_r($removed);
?>

A Array\n(\n [0] => 1\n [1] => 9\n [2] => 8\n [3] => 5\n)\nArray\n(\n [0] => 2\n [1] => 3\n [2] => 4\n)

B Array\n(\n [0] => 1\n [1] => 2\n [2] => 3\n [3] => 4\n [4] => 5\n [5] => 9\n [6] => 8\n)\nArray\n()

C Array\n(\n [0] => 9\n [1] => 8\n)\nArray\n(\n [0] => 1\n [1] => 2\n [2] => 3\n [3] => 4\n [4] => 5\n)

D Array\n(\n [0] => 1\n [1] => 9\n [2] => 8\n)\nArray\n(\n [0] => 2\n [1] => 3\n)

💡 Hint

array_splice removes elements and replaces them with new ones, returning the removed elements.

array_splice removes 3 elements starting at index 1 (2,3,4) and inserts [9,8] in their place. The original array is modified, and the removed elements are returned.

🔧 Debug

advanced

What error does this PHP code raise?

Examine this PHP snippet. What error will it produce when run?

PHP

<?php
$array = [5, 10, 15];
$result = array_slice($array, -1, -1);
print_r($result);
?>

A Array\n() (an empty array)

B Warning: Length parameter cannot be negative in array_slice()

C Array\n(\n [0] => 15\n)

D Fatal error: Uncaught Exception

💡 Hint

Check the meaning of negative length in array_slice.

array_slice does not accept a negative length parameter. It triggers a warning and returns an empty array.

❓ Predict Output

advanced

What is the output of this PHP array_splice with no length parameter?

What will this PHP code print?

PHP

<?php
$array = [100, 200, 300, 400];
$removed = array_splice($array, 2);
print_r($array);
print_r($removed);
?>

A Array\n(\n [0] => 300\n [1] => 400\n)\nArray\n(\n [0] => 100\n [1] => 200\n)

B Array\n(\n [0] => 100\n [1] => 200\n [2] => 300\n [3] => 400\n)\nArray\n()

C Array\n(\n [0] => 100\n [1] => 200\n)\nArray\n(\n [0] => 300\n [1] => 400\n)

D Array\n()\nArray\n(\n [0] => 100\n [1] => 200\n [2] => 300\n [3] => 400\n)

💡 Hint

If length is omitted, array_splice removes all elements from offset to end.

array_splice removes all elements from index 2 to the end and returns them. The original array is shortened accordingly.

🧠 Conceptual

expert

How many elements remain in the array after this PHP array_splice operation?

Given this PHP code, how many elements will remain in $array after the operation?

PHP

<?php
$array = [7, 14, 21, 28, 35, 42];
array_splice($array, 2, 2, [99, 100, 101]);
?>

A 5

B 4

C 6

D 7

💡 Hint

Count how many elements are removed and how many are inserted.

array_splice removes 2 elements starting at index 2 and inserts 3 new elements. So total elements = original 6 - 2 + 3 = 7.