PHP array_flip() Function (original) (raw)

Last Updated : 20 Jun, 2023

This built-in function of PHP is used to exchange elements within an array, i.e., exchange all keys with their associated values in an array and vice-versa. We must remember that the values of the array need to be valid keys, i.e. they need to be either integer or string. A warning will be thrown if a value has the wrong type, and the key/value pair in question will not be included in the result.Examples:

Input : array = ("aakash" => 20, "rishav" => 40, "gaurav" => 60) Output: Array ( [20] => aakash [40] => rishav [60] => gaurav ) Explanation: The keys and values are exchanged and the last key or value is taken.

Input : array = ("aakash" => "rani", "rishav" => "sristi", "gaurav" => "riya", "laxman" => "rani") Output: Array ( [rani] => laxman [sristi] => rishav [riya] => gaurav )

Syntax:

array array_flip($array)

Parameters: The function takes only one parameter $array that refers to the input array.Return Type: This function returns another array, with the elements exchanged or flipped, it returns null if the input array is invalid. Below program illustrates the working of array_flip() function in PHP:Example 1:

PHP `

result=arrayflip(result = array_flip(result=arrayf​lip(array); return($result); } $array = array("aakash" => "rani", "rishav" => "sristi", "gaurav" => "riya", "laxman" => "rani"); print_r(Flip($array)); ?>

`

Output:

Array ( [rani] => laxman [sristi] => rishav [riya] => gaurav )

If multiple values in the array are the same, then on the use of the array_flip() function, only the key with the maximum index (after swap) will be added to the array. (This is done to ensure that no keys have duplicates.)Example 2:

php `

result=arrayflip(result = array_flip(result=arrayf​lip(array); return($result); } //make the array $array = array("a" => 1, "b" => 1, "c" => 2); //print all resultant values print_r(Flip($array)); ?>

`

Output:

Array ( [1] => b [2] => c )

References: https://www.php.net/manual/en/function.array-flip.php