PHP array_merge
Summary: in this tutorial, you will learn how to use the PHP array_merge()
function to merge one or more arrays into one.
Introduction to the PHP array_merge() function
To merge one or more array into an array, you use the array_merge()
function:
array_merge ( array ...$arrays ) : array
Code language: PHP (php)
The array_merge()
function accepts one or more arrays and returns a new array that contains the elements from the input arrays.
The array_merge()
function appends the elements of the next array to the last element of the previous one.
When the elements in the input arrays have the string keys, the later value for that key will overwrite the previous one.
However, if the array_merge()
function will not overwrite the values with the same numeric keys. Instead, it renumbers the numeric keys starting from zero in the result array.
Starting from PHP 7.4.0, you can call the array_merge()
function without any arguments. In this case, the function will return an empty array.
PHP array_merge() function examples
Let’s take some examples of using the array_merge()
function.
1) Simple array_merge() function example
The following example uses the array_merge()
function to merge two arrays into one:
$server_side = ['PHP'];
$client_side = ['JavaScript', 'CSS', 'HTML'];
$full_stack = array_merge($server_side, $client_side);
print_r($full_stack);
Code language: HTML, XML (xml)
Output:
Array
(
[0] => PHP
[1] => JavaScript
[2] => CSS
[3] => HTML
)
Code language: PHP (php)
How it works.
- First, define two indexed arrays:
$server_side
and$client_side
. - Second, merge the
$server_side
and$client_side
arrays into one array using thearray_merge()
function. - Third, show the result array.
As you can see clearly from the output, the array_merge()
function renumbers the numeric keys of the elements in the result array.
2) Using array_merge() function with string keys
The following example uses the array_merge()
function with the array with the string keys:
$before = [
'PHP' => 2,
'JavaScript' => 4,
'HTML' => 4,
'CSS' => 3
];
$after = [
'PHP' => 5,
'JavaScript' => 5,
'MySQL' => 4,
];
$skills = array_merge($before, $after);
print_r($skills);
Code language: HTML, XML (xml)
Output:
Array
(
[PHP] => 5
[JavaScript] => 5
[HTML] => 4
[CSS] => 3
[MySQL] => 4
)
Code language: PHP (php)
Because both $before
and $after
arrays have the same elements with the same string keys PHP
and JavaScript
, the elements in the $before
array overwrites the ones in the $after
array.
Summary
- Use the PHP
array_merge()
function to merge elements of two or more arrays into a single array.