PHP sort Function

last modified March 13, 2025

The PHP sort function sorts an array in ascending order. It modifies the original array and returns true on success.

Basic Definition

The sort function sorts an array by values in ascending order. It maintains index association for associative arrays by default.

Syntax: sort(array &$array, int $flags = SORT_REGULAR): bool. The flags parameter modifies the sorting behavior. The function returns true.

Basic sort Example

This demonstrates sorting a simple numeric array in ascending order.

basic_sort.php

<?php

$numbers = [3, 1, 4, 1, 5, 9, 2, 6];
sort($numbers);

print_r($numbers);

The array is sorted in ascending order. Note that the original array is modified, and numeric indices are reordered starting from 0.

Sorting String Arrays

The sort function works with string arrays using alphabetical order.

string_sort.php

<?php

$fruits = ["banana", "apple", "orange", "pear"];
sort($fruits);

print_r($fruits);

Strings are sorted alphabetically. The sorting is case-sensitive, with uppercase letters coming before lowercase ones in default sorting.

Sorting With Flags

PHP provides sorting flags to modify the sorting behavior. This example uses SORT_NUMERIC for proper numeric comparison.

sort_flags.php

<?php

$mixed = ["10", 2, "100", 5, 1];
sort($mixed, SORT_NUMERIC);

print_r($mixed);

With SORT_NUMERIC, string numbers are properly compared as numeric values. Without this flag, they would be compared as strings.

Sorting Associative Arrays

Sorting associative arrays with sort loses the original keys.

associative_sort.php

<?php

$ages = ["Peter" => 35, "Ben" => 37, "Joe" => 43];
sort($ages);

print_r($ages);

The keys are replaced with numeric indices. To preserve key-value association, use asort instead of sort.

Case-Insensitive Sorting

Use SORT_STRING | SORT_FLAG_CASE for case-insensitive sorting.

case_insensitive_sort.php

<?php

$names = ["John", "alice", "bob", "Alice"];
sort($names, SORT_STRING | SORT_FLAG_CASE);

print_r($names);

The combination of flags enables case-insensitive comparison. Note that original case is preserved in the sorted array, only comparison changes.

Best Practices

Preserve Keys: Use asort for associative arrays.
Flag Selection: Choose appropriate flags for data type.
Copy Arrays: Make a copy if you need the original order.
Large Arrays: Consider usort for complex sorts.

Source

PHP sort Documentation

This tutorial covered the PHP sort function with practical examples showing its usage for various sorting 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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