How to use array_merge() and array_combine() in PHP ?

Last Updated : 14 Jun, 2024

In this article, we will discuss about how to use array_merge() and array_combine() functions in PHP. Both functions are array based functions used to combine two or more arrays using PHP. We will see each function with syntax and implementation

array_merge() Function

This function merges the two or more arrays such that all the arrays have keys and values. The arrays are appended at the end of the first array.

Syntax:

array_merge( array1, array2, ..., array n )

Parameters: Arrays are the input arrays to be merged.

Return type: Single array with merged elements.

Example: PHP example to merge two arrays.

PHP

<?php

// Define array1 with keys and values
$array1 = array(
      "subject1" => "Python",
      "subject2" => "sql"
);

// Define array2 with keys and values
$array2 = array(
      "subject3" => "c/c++",
      "subject4" => "java"
);

// Merge both array1 and array2
$final = array_merge($array1, $array2);

// Display merged array
print_r($final);

?>

Output

Array
(
    [subject1] => Python
    [subject2] => sql
    [subject3] => c/c++
    [subject4] => java
)

Example 2: Merge multiple arrays.

PHP

<?php

// Define array1 with keys and values
$array1 = array(
      "subject1" => "Python",
      "subject2" => "sql"
);

// Define array2 with keys and values
$array2 = array(
      "subject3" => "c/c++",
      "subject4" => "java"
);

// Define array3 with keys and values
$array3 = array(
      "subject5" => "CN",
      "subject6" => "OS"
);

// Define array4 with keys and values
$array4 = array(
      "subject7" => "data mining",
      "subject8" => "C#"
);

// Merge all arrays
$final = array_merge($array1, 
         $array2, $array3, $array4);

// Display merged array
print_r($final);

?>

Output

Array
(
    [subject1] => Python
    [subject2] => sql
    [subject3] => c/c++
    [subject4] => java
    [subject5] => CN
    [subject6] => OS
    [subject7] => data mining
    [subject8] => C#
)

array_combine() Function

This function combine only two arrays with one array containing keys and another array containing values.

Syntax:

array_combine(array1, array2)

Parameters:

array1 is the first array with keys.
array2 is the second array with values.

Return Value: It returns the combined array.

Example: PHP program to combine arrays.

PHP

<?php

// Define array1 with keys 
$array1 = array("subject1" ,"subject2");

// Define array2 with values
$array2 = array( "c/c++", "java");

// Combine two arrays
$final = array_combine($array1, $array2);

// Display merged array
print_r($final);

?>

Output

Array
(
    [subject1] => c/c++
    [subject2] => java
)

Example 2:

PHP

<?php

// Define array1 with keys 
$array1 = array("subject1", 
          "subject2", "subject3", "subject4");

// Define array2 with  values
$array2 = array( "c/c++", "java", "Python", "HTML");

// Combine two arrays
$final = array_combine($array1, $array2);

// Display merged array
print_r($final);

?>

Output

Array
(
    [subject1] => c/c++
    [subject2] => java
    [subject3] => Python
    [subject4] => HTML
)

Difference table of array_merge() and array_combine() in PHP

Feature/Aspect	`array_merge()`	`array_combine()`
Purpose	Combines two or more arrays into one	Creates an associative array by combining keys and values
Input	Accepts multiple arrays	Requires two arrays: one for keys and one for values
Key Handling	Overwrites values if keys are duplicated (for associative arrays)	Keys from the first array, values from the second array
Output	Returns a single merged array	Returns an associative array
Use Case	Merging indexed or associative arrays	Creating an associative array from two separate arrays