PHP array_combine() Function

Hello folks! welcome to another section of our tutorial on PHP. In this tutorial guide, we are going to be studying about array_combine() Function in PHP.

The PHP array_combine() function takes two different or the same arrays as input and then creates a new array by using the values from the keys array as keys and then the values array is used as the corresponding values.

While passing two arrays in the function, make sure the number of elements in both arrays are the same, else it will return an error.

Syntax

Following below is the syntax to use this function -

array array_combine ( array $keys, array $values );

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Parameter Details

Sr.No	Parameter & Description
1	keys (mandatory) First array whose values will be used as the keys to create a new array.
2	values (mandatory) Second array whose values will be used as the values to create the new array.

Return Value

This returns a combined array, else False if the number of elements for each array is not equal, or if the arrays are empty.

PHP Version

This function was first lunched as part of core PHP v 5.0.0.

Errors/Exceptions

If the number of elements in the keys and values arrays does not match, it throws E_WARNING.

Example1

The following is an example where we're using two different arrays to combine them into one array -

<?php
   $a = array('green', 'red', 'yellow');
   $b = array('avocado', 'apple', 'banana');
   $c = array_combine($a, $b);

   print_r($c);
?>

Output

When the above code is executed, it will produce the following result -

Array
(
    [green] => avocado
    [red] => apple
    [yellow] => banana
)

Example2

The following below is an example where we're using two different arrays to combine them into just a one array, but this time around we are making use of unequal number of elements in both arrays -

<?php
   $a = array('green', 'red', 'yellow');
   $b = array('avocado', 'apple');
   $c = array_combine($a, $b);

   print_r($c);
?>

Output

When the above code is executed, it will produce the following result -

PHP Warning:  array_combine(): Both parameters should have an equal number of elements in main.php on line 4

Example3

If two keys are the same, then the second one will dominate but it is absolutely valid -

<?php
   $a = array('green', 'green', 'yellow');
   $b = array('avocado', 'apple', 'banana');
   $c = array_combine($a, $b);

   print_r($c);
?>

Output

When the above code is executed, it will produce the following result -

Array
(
    [green] => apple
    [yellow] => banana
)

Example4

We can create a new array using the same input array, try out the following example -

<?php
   $a = array('green', 'green', 'yellow');
   $c = array_combine($a, $a);

   print_r($c);
?>

Output

When the above code is executed, it will produce the following result -

Array
(
    [green] => green
    [yellow] => yellow
)

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Alright guys! This is where we are rounding up for this tutorial post. In our next tutorial, we will discuss about PHP's array_count_values() Function.

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