PHP array_flip: Swap Keys & Values

The function array_flip() in PHP is used to swap the keys and values in an array. Specifically, it takes the keys in the array and uses them as values, while using the values as keys, then returns a new array.

Here is a detailed explanation of the array_flip() function:

1. Syntax: array array_flip(array $array)
2. Parameters:

   $array: the array in which key-value pairs are to be swapped.

3. Return value:

   Return a new array where the values in the original array become the keys of the new array, and the keys in the original array become the values of the new array.

4. Output:“`
   Array(
   [#ff0000] => red
   [#00ff00] => green
   [#0000ff] => blue
   )
   “`
5. Note:

   If the values in the original array are not unique, the later values will overwrite the earlier values during the key-value exchange. If the values in the original array are strings and contain non-scalar types (such as arrays), the array_flip() function will return a NULL value.

By using the array_flip() function, you can easily swap the keys and values in an array, allowing you to quickly look up keys corresponding to a value. This is useful for situations where you need to find the key associated with a given value.