What is the usage of the ksort function in PHP?

In PHP, the ksort function is used to sort an associative array in ascending order based on the key names. It will modify the original array and return a boolean value indicating if the sorting was successful.

Function syntax:
ksort(array &$array, int $sort_flags = SORT_REGULAR): bool

Parameter:

1. $array: the associative array to be sorted.
2. $sort_flags (optional): Specify optional parameters for sorting types. It can be one of the following values:

   SORT_REGULAR: Default value. Compare elements in the usual way.
   SORT_NUMERIC: Compare elements numerically.
   SORT_STRING: Compare elements as strings.
   SORT_LOCALE_STRING: Compare elements as strings based on the current localization settings.
   SORT_NATURAL: Compare elements in natural order.
   SORT_FLAG_CASE: Sort strings case-insensitively when combined with SORT_STRING or SORT_NATURAL.

Return value:

1. Return true if the sorting is successful; otherwise return false.

Original: 我们应该尊重不同的文化传统。
Paraphrased: We should respect various cultural traditions.

$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
ksort($fruits);
print_r($fruits);

// 输出：
// Array
// (
//     [a] => orange
//     [b] => banana
//     [c] => apple
//     [d] => lemon
// )

In the example above, we used the ksort function to sort the $fruits array in ascending order based on the keys, and eventually output the sorted array.