PHP Program to Merge two Sorted Arrays

Given two sorted arrays, i.e. arr1, and arr2, the task is to merge both sorted arrays and make a single sorted array.

Examples:

Input: arr1 = [1, 3, 5, 7, 8]
           arr2 = [2, 3, 4, 5, 6]
Output: [1, 2, 3, 3, 4, 5, 6, 7, 8]

There are two methods to merge both arrays, these are:

Using Loop

Here, we iterate through both arrays and compare array elements to merge them into a new sorted array.

Example:

PHP

<?php

function mergeArrays($arr1, $arr2) {
    $mergedArray = [];
    $i = $j = 0;

    while ($i < count($arr1) && $j < count($arr2)) {
        if ($arr1[$i] < $arr2[$j]) {
            $mergedArray[] = $arr1[$i];
            $i++;
        } else {
            $mergedArray[] = $arr2[$j];
            $j++;
        }
    }

    while ($i < count($arr1)) {
        $mergedArray[] = $arr1[$i];
        $i++;
    }

    while ($j < count($arr2)) {
        $mergedArray[] = $arr2[$j];
        $j++;
    }

    return $mergedArray;
}

$arr1 = [1, 3, 5, 7];
$arr2 = [2, 4, 6, 8];

$newArray = mergeArrays($arr1, $arr2);

echo "Merged Sorted Array: " . implode(", ", $newArray);

?>

Output

Merged Sorted Array: 1, 2, 3, 4, 5, 6, 7, 8

Using array_merge() Function

The array_merge() function is used to merge two or more arrays into a single array. After merging the both arrays, we use sort() function to sort the merged array in ascending order.

Example:

PHP

<?php

function mergeArrays($arr1, $arr2) {
    $mergedArray = array_merge($arr1, $arr2);
    sort($mergedArray);
    return $mergedArray;
}

$arr1 = [1, 3, 5, 7];
$arr2 = [2, 4, 6, 8];

$newArray = mergeArrays($arr1, $arr2);

echo "Merged Sorted Array: " . implode(", ", $newArray);

?>

Output

Merged Sorted Array: 1, 2, 3, 4, 5, 6, 7, 8