PHP Array Exercises : Merge two arrays

Last update on May 30 2025 13:14:09 (UTC/GMT +8 hours)

11. Merge Arrays by Index

Write a PHP program to merge (by index) the following two arrays.

Sample arrays :
$array1 = array(array(77, 87), array(23, 45));
$array2 = array("w3resource", "com");

Sample Solution:

PHP Code:

<?php
// Define a multidimensional array $array1
$array1 = array(array(77, 87), array(23, 45));

// Define a simple array $array2
$array2 = array("w3resource", "com");

// Define a function named 'merge_arrays_by_index' that merges elements based on their indexes
function merge_arrays_by_index($x, $y)
{
    // Create an empty temporary array
    $temp = array();
    
    // Add the first element $x to the temporary array
    $temp[] = $x;

    // Check if $y is a scalar value
    if (is_scalar($y))
    {
        // If $y is scalar, add it directly to the temporary array
        $temp[] = $y;
    }
    else
    {
        // If $y is an array, iterate through its key-value pairs and add values to the temporary array
        foreach ($y as $k => $v)
        {
            $temp[] = $v;
        }
    }

    // Return the temporary array
    return $temp;
}

// Output HTML preformatted text
echo '<pre>';

// Use array_map to apply 'merge_arrays_by_index' to corresponding elements of $array2 and $array1
print_r(array_map('merge_arrays_by_index', $array2, $array1));
?>

Output:

<pre>Array                                                  
(                                                           
    [0] => Array                                            
        (                                                   
            [0] => w3resource                               
            [1] => 77                                       
            [2] => 87                                       
        )                                                   
                                                            
    [1] => Array                                            
        (                                                   
            [0] => com                                      
            [1] => 23                                       
            [2] => 45                                       
        )                                                   
                                                            
)

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to merge two two-dimensional arrays by interleaving their elements based on index.
Write a PHP function that takes two arrays of equal length, merges them by alternation, and returns a nested array.
Write a PHP program to combine two arrays element-wise and store the result as sub-arrays within a larger array.
Write a PHP script to merge two arrays where one contains keys and the other contains values, then output the combined result as a multidimensional array.

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