The array_multisort() is an inbuilt function in PHP which is used to sort multiple arrays at once or a multi-dimensional array with each individual dimension.
With this function, one should remember that string keys will be maintained, but numeric keys will be re-indexed, starting at 0 and increases by 1.
bool array_multisort($array1, sorting_order, sorting_type, $array2..)
Parameters: The array generally takes one parameter that is the array which needs to be sorted. But in addition, the function can take two more optional parameters sorting_order and sorting_type.
- $array1: This parameter specifies the array which we want to sort.
- sorting_order: This parameter specifies the order to use i.e. in ascending or descending order. The default value of this parameter is SORT_ASC. That is, sorting in ascending order. In order to sort in descending order we will have to set this parameter to SORT_DESC.
sorting_type: This parameter specifies the sort options for the arrays and they are as follows:
- SORT_REGULAR: Compare elements regularly(Standard ASCII).
- SORT_NUMERIC: Compare elements as numeric-values.
- SORT_STRING: Compare elements as string values.
- SORT_LOCALE_STRING: Compare elements as string, based on the current locale.
- SORT_NATURAL: Compare elements as strings using “natural ordering”.
- SORT_FLAG_CASE: Can be combined (bitwise OR) with SORT_STRING or SORT_NATURAL to sort strings case-insensitively.
If we want to sort multiple arrays, we can pass them as parameters like $array2, $array3… followed by their sorting_order, sorting_type.
Return value: The array_multisort() function returns a boolean value. That is it will return TRUE on success and FALSE on failure.
Note:If two members on comparing become equal, their relative order in sorted array is undefined.
Below programs illustrate the array_multisort() function:
Array (  => Bear  => Cat  => Dog  => Horse  => Lion  => Zebra )
Array (  => Cat  => Dog ) Array (  => Missy  => Fido )
Array (  => Cat  => Dog  => Dog ) Array (  => Missy  => Pluto  => Fido )