Understanding PHP’s array_merge() Function

PHP is a powerful programming language with many built‑in functions, and this article introduces one of the most commonly used functions: array_merge().

The array_merge() function merges two or more arrays into a single new array and returns that combined array.

Syntax:

array_merge ( array $array1 [, array $... ] ) : array

The function takes at least one required parameter $array1, which is the first array to be merged, and an optional variadic list of additional arrays.

It returns all elements from the supplied arrays; if the same key appears in multiple arrays, later values overwrite earlier ones.

Code Example:

<?php
    $array1 = array('A'=>'Apple','B'=>'Ball','C'=>'Cat');
    $array2 = array('D'=>'Dog','E'=>'Egg','F'=>'Fan');

    $result = array_merge($array1, $array2);
    print_r($result);
?>

In this example, two associative arrays are defined, merged with array_merge(), and the result is stored in $result. The print_r() function then outputs the merged array.

Running the script produces the following output:

Array
(
    [A] => Apple
    [B] => Ball
    [C] => Cat
    [D] => Dog
    [E] => Egg
    [F] => Fan
)

The output shows that the two original arrays have been successfully combined into one without duplicate keys.

Beyond this simple case, array_merge() can merge any number of arrays by passing them as additional arguments; when duplicate keys exist, the later array’s value overwrites the earlier one.

Whether developing web applications or other types of software, array_merge() is a practical and efficient tool for handling array data in PHP.