Merge Two Arrays In PHP

Merging two arrays in PHP can prove to be a helpful feature in many coding scenarios. This article will provide a guide on how you can easily perform this task using some built-in functions in PHP.

Code snippet for Merging Two Arrays in PHP

In PHP, the simplest and most commonly used function to merge two arrays is the array_merge() function.

Here’s a basic example:

<?php
    $array1 = array("color" => "red", 2, 4);
    $array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
    $result = array_merge($array1, $array2);
    print_r($result);
?>

In this example, calling print_r() on the variable $result should output this:

Array
(
    [color] => green
    [0] => 2
    [1] => 4
    [2] => a
    [3] => b
    [shape] => trapezoid
    [4] => 4
)

Code Explanation for Merging Two Arrays in PHP

The array_merge() function in PHP takes two or more arrays as its arguments and merges them into a single array. If the input arrays have the same string keys, the later value will overwrite the previous one.

In our example, we have two arrays, $array1 and $array2. $array1 has a key/value pair of “color” => “red” and $array2 has a key/value pair of “color” => “green”. When these arrays are merged uisng array_merge($array1, $array2), and since both arrays contain the string key “color”, the latter in the sequence (“green” from $array2) overwrites the former (“red” from $array1).

The second aspect to note is that while merging, numeric keys are renumbered starting from zero in the result array. Hence, you will notice that in the final result array, the merged elements with numerical keys are ordered starting from zero.

The order of merged elements in the resulting array is the same as the order they had in their original arrays.

Using array_merge() function is highly effective especially when you need to combine datasets that have some overlaps or if you want to stack lists. Whether you’re dealing with numerical data strings or associative arrays, this function does it all. Be mindful about key overlaps which would result in overwritten data.