PHP has a rich library of predefined functions, and that also includes different sorting functions. It has different functions to sort a list of items in an array either by value or by key/index. We can also keep the association of the array's values with their respective keys while doing the sorting. Another important function of PHP is the built-in function for sorting a multi-dimensional array. Here is a summary of these functions:
|
Function name |
Purpose |
|
sort() |
This sorts an array in ascending order. Value/key association is not preserved. |
|
rsort() |
Sort an array in reverse/descending order. Index/key association is not preserved. |
|
asort() |
Sort an array while maintaining index association. |
|
arsort() |
Sort an array in reverse order and maintain index association. |
|
ksort() |
Sort an array by key. It maintains key to data correlations. This is useful mainly for associative arrays. |
|
krsort() |
Sort an array by key in reverse order. |
|
natsort() |
Sort an array using a natural order algorithm, and Value/key association is maintained. |
|
natcasesort() |
Sort an array using a case insensitive "natural order" algorithm, and Value/key association is maintained. |
|
usort() |
Sort an array by values using a user-defined comparison function, and Value/Key association is not maintained. |
|
uksort() |
Sort an array by keys using a user-defined comparison function, and Value/key association is maintained. |
|
uasort() |
Sort an array by values using a user-defined comparison function, and Value/key association is maintained. |
For sort, rsort, ksort, krsort, asort, and arsort, the following sorting flags are available:
- SORT_REGULAR: compare items as they are (don't change types)
- SORT_NUMERIC: compare items numerically
- SORT_STRING: compare items as strings
- SORT_LOCALE_STRING: compare items as strings, based on the current locale
- SORT_NATURAL: compare items as strings using "natural ordering"