The asort() function in PHP is used to sort an associative array in ascending order, according to the values, while maintaining the key association (i.e., keys are preserved).

✅ Syntax:

asort(array &$array, int $flags = SORT_REGULAR): bool

• &$array: The input array (passed by reference and modified in place)
• flags: Optional. Specifies the sorting behavior. Common flags:
  • SORT_REGULAR – Default: Compare items normally
  • SORT_NUMERIC – Compare items numerically
  • SORT_STRING – Compare items as strings
  • SORT_NATURAL – Compare items using "natural order" (like natsort)

🔸 Example 1: Basic Usage

$fruits = array("a" => "banana", "b" => "apple", "c" => "mango");
asort($fruits);

print_r($fruits);

Output:

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

➡️ Values are sorted, but the keys (a, b, c) remain associated with their original values.

🔸 Example 2: Numeric Array

$numbers = array("x" => 40, "y" => 10, "z" => 100);
asort($numbers);

print_r($numbers);

Output:

Array
(
    [y] => 10
    [x] => 40
    [z] => 100
)

➡️ Sorted by values in ascending order, keys preserved.

🔸 Example 3: With SORT_STRING

$data = array("x" => "20", "y" => "100", "z" => "3");
asort($data, SORT_STRING);

print_r($data);

Output:

Array
(
    [y] => 100
    [x] => 20
    [z] => 3
)

➡️ String-based sorting: "100" comes before "20" and "3".

🔁 Related Functions:

• arsort() – Sort by values in descending order, maintain keys
• ksort() – Sort by keys in ascending order
• krsort() – Sort by keys in descending order
• sort() – Sort by values, reset keys (numeric array)
• usort() – User-defined sort by values