PHP array_combine() Function

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Definition and Usage

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

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

Syntax

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

Parameters

Return Values

PHP array_combine() function returns the combined array otherwise FALSE if the number of elements for each array isn't equal or if the arrays are empty.

PHP Version

This function was first introduced in PHP Version 5.0.0.

Errors/Exceptions

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

Example

Following is the example where we are 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);
?>

This will produce following result −

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

Example

Following is the example where we are using two different arrays to combine them into one array, but this time we are using unequal number of elements in both the arrays −

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

   print_r($c);
?>

This will produce following result −

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

Example

If two keys are the same, the second one prevails but it is absolutely valid −

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

   print_r($c);
?>

This will produce following result −

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

Example

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);
?>

This will produce following result −

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