Array slice and splice in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the array_slice() function do in PHP?

It returns a portion of an array without modifying the original array. You specify the start position and length of the slice.

beginner

How does array_splice() differ from array_slice()?

array_splice() removes a portion of an array and can replace it with new elements. It modifies the original array.

intermediate

What happens if you use a negative start index in array_slice()?

The slice starts that many elements from the end of the array. For example, -2 means start from the second last element.

intermediate

What does array_splice($array, 2, 3, ['a', 'b']) do?

It removes 3 elements from $array starting at index 2, then inserts 'a' and 'b' at that position, modifying $array.

intermediate

Does array_slice() preserve keys by default?

No, by default it reindexes the returned array starting from 0. You can preserve keys by passing true as the fourth argument.

Which function modifies the original array in PHP?

A array_map()

B array_slice()

C array_merge()

D array_splice()

array_splice() changes the original array by removing and optionally replacing elements.

What does array_slice($arr, 1, 2) return?

A Two elements starting from index 1

B Elements from index 1 to 2 inclusive

C All elements except the first

D The entire array

It returns 2 elements starting at index 1, without modifying the original array.

How do you preserve keys when using array_slice()?

A Pass true as the fourth argument

B Pass false as the third argument

C Use array_splice() instead

D Keys are always preserved

Passing true as the fourth argument preserves the original keys in the returned slice.

What does array_splice($arr, 0, 0, ['x']) do?

A Removes the first element

B Inserts 'x' at the start without removing elements

C Replaces the first element with 'x'

D Returns an empty array

It inserts 'x' at the start without removing any elements because length is 0.

If you want to get the last 3 elements of an array without changing it, which is best?

A array_splice($arr, -3)

B array_shift() three times

C array_slice($arr, -3)

D array_pop() three times

array_slice($arr, -3) returns the last 3 elements without modifying the original array.

Explain the difference between array_slice() and array_splice() in PHP.

Think about whether the original array changes or not.

Describe how to use array_splice() to remove elements and insert new ones.

Remember it works like cutting out and pasting in new pieces.