Guide to writing a custom sorting algorithm for PHP arrays

How to write a custom PHP array sorting algorithm? Bubble sort: Sorts an array by comparing and exchanging adjacent elements. Selection sort: Select the smallest or largest element each time and swap it with the current position. Insertion sort: Insert elements one by one into the sorted part.

Guidelines for writing PHP array custom sorting algorithm

Introduction
Array sorting is programming A common task that allows us to reorganize elements in an array based on specific criteria. PHP provides a variety of built-in sorting algorithms, but sometimes we need to sort arrays based on custom logic, which requires us to write our own custom sorting algorithm.

Bubble sort
Bubble sort is a simple sorting algorithm that sorts an array by repeatedly comparing adjacent elements and exchanging their positions.

function bubbleSort(array &$arr) {
    $n = count($arr);
    for ($i = 0; $i < $n - 1; $i++) {
        for ($j = 0; $j < $n - $i - 1; $j++) {
            if ($arr[$j] > $arr[$j + 1]) {
                $tmp = $arr[$j];
                $arr[$j] = $arr[$j + 1];
                $arr[$j + 1] = $tmp;
            }
        }
    }
}

Selection sort
Selection sort is a sorting algorithm based on selecting the smallest or largest element and exchanging it with its current position.

function selectionSort(array &$arr) {
    $n = count($arr);
    for ($i = 0; $i < $n - 1; $i++) {
        $min_idx = $i;
        for ($j = $i + 1; $j < $n; $j++) {
            if ($arr[$j] < $arr[$min_idx]) {
                $min_idx = $j;
            }
        }

        $tmp = $arr[$i];
        $arr[$i] = $arr[$min_idx];
        $arr[$min_idx] = $tmp;
    }
}

Insertion sort
Insertion sort is a sorting algorithm based on inserting elements one by one into an ordered part.

function insertionSort(array &$arr) {
    $n = count($arr);
    for ($i = 1; $i < $n; $i++) {
        $key = $arr[$i];
        $j = $i - 1;

        while ($j >= 0 && $arr[$j] > $key) {
            $arr[$j + 1] = $arr[$j];
            $j--;
        }

        $arr[$j + 1] = $key;
    }
}

Practical case
Let us use the bubble sort algorithm to sort the following PHP array in ascending order:

$arr = [5, 2, 8, 3, 1];

Call the bubble sort function:

bubbleSort($arr);

Sorted array:

[1, 2, 3, 5, 8]

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