Using PHP array_flip() to Reverse Array Keys and Values

In PHP, the array_flip() function is commonly used to invert an array's keys and values, returning a new array where each original value becomes a key and each original key becomes its corresponding value.

Basic Syntax:

array array_flip ( array $array )

Parameter:

The $array parameter is the array to be flipped.

Return Value:

The function returns the flipped array; if the argument is not a valid array, it returns bool(false). Below is an example of using array_flip():

$array = array('a' => 'apple', 'b' => 'banana', 'c' => 'cherry');
$flippedArray = array_flip($array);
print_r($flippedArray);

Output:

Array
(
    [apple] => a
    [banana] => b
    [cherry] => c
)

If the original array contains duplicate values, only the last key will be kept in the flipped array, as demonstrated in the following example where two keys share the value “banana”:

$array = array('a' => 'apple', 'b' => 'banana', 'c' => 'banana');
$flippedArray = array_flip($array);
print_r($flippedArray);

Output:

Array
(
    [apple] => a
    [banana] => c
)

When using array_flip(), ensure that the original array's values are unique or can be used as unique string keys; otherwise the result may not be as expected.