PHP array_slice Function

last modified March 13, 2025

The PHP array_slice function extracts a slice of an array. It's useful for getting portions of arrays without modifying the original array.

Basic Definition

The array_slice function returns selected parts of an array. It can extract elements from any position with specified length.

Syntax: array_slice(array $array, int $offset, ?int $length = null, bool $preserve_keys = false): array. Negative offsets count from the end of the array.

Basic array_slice Example

This shows how to extract a simple slice from an array starting at position 2.

basic_array_slice.php

<?php

$fruits = ['apple', 'banana', 'cherry', 'date', 'elderberry'];
$slice = array_slice($fruits, 2);

print_r($slice);

This extracts elements starting from index 2 to the end. The output will be ['cherry', 'date', 'elderberry']. Original array remains unchanged.

Specifying Length Parameter

This example demonstrates how to specify both offset and length parameters.

length_parameter.php

<?php

$numbers = [1, 2, 3, 4, 5, 6, 7, 8];
$slice = array_slice($numbers, 3, 3);

print_r($slice);

This extracts 3 elements starting from index 3. The output will be [4, 5, 6]. The length parameter limits how many elements to include in the slice.

Negative Offset

Using negative offset starts the slice from the end of the array.

negative_offset.php

<?php

$letters = ['a', 'b', 'c', 'd', 'e', 'f'];
$slice = array_slice($letters, -3, 2);

print_r($slice);

This starts 3 elements from the end and takes 2 elements. The output will be ['d', 'e']. Negative offsets are useful when you know positions from the end.

Preserving Keys

The preserve_keys parameter maintains original array keys in the slice.

preserve_keys.php

<?php

$assoc = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];
$slice = array_slice($assoc, 1, 2, true);

print_r($slice);

This preserves the original keys 'b' and 'c' in the slice. The output will be ['b' => 2, 'c' => 3]. Without true, keys would be reindexed starting from 0.

Combining Parameters

This example combines negative offset and length with key preservation.

combined_parameters.php

<?php

$data = [10, 20, 30, 40, 50, 60];
$slice = array_slice($data, -4, 3, true);

print_r($slice);

This starts 4 elements from the end, takes 3 elements, and preserves keys. The output will be [2 => 30, 3 => 40, 4 => 50] with original indices.

Best Practices

Bounds Checking: Verify offsets exist to avoid empty slices.
Key Preservation: Use true for associative arrays.
Negative Indices: Useful for end-relative operations.
Immutability: Remember original array isn't modified.

Source

PHP array_slice Documentation

This tutorial covered the PHP array_slice function with practical examples showing its usage for array extraction scenarios.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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