Custom Key Sorting Without Using uksort()  in PHP

The uksort() function in PHP sorts an array by its keys using a user-defined comparison function. If you want to implement the same functionality manually without using uksort(), you can use a sorting algorithm like Bubble Sort or Selection Sort on the array’s keys.

Method: Custom Sorting by Keys Without uksort()

We will manually sort the keys of an associative array using a Bubble Sort algorithm with a custom comparison function.

Code Example:

<?php
$array = [
    "apple" => 3,
    "orange" => 1,
    "banana" => 2,
    "grape" => 5,
];

// Custom comparison function for keys (sorting alphabetically)
function customKeyCompare($a, $b) {
    return strcmp($a, $b); // Compare keys as strings
}

// Bubble Sort with custom key comparison function
$keys = array_keys($array);
$length = count($keys);

for ($i = 0; $i < $length - 1; $i++) {
    for ($j = 0; $j < $length - $i - 1; $j++) {
        if (customKeyCompare($keys[$j], $keys[$j + 1]) > 0) {
            // Swap the keys if they are not in order
            $temp = $keys[$j];
            $keys[$j] = $keys[$j + 1];
            $keys[$j + 1] = $temp;
        }
    }
}

// Rebuild the sorted array based on the sorted keys
$sortedArray = [];
foreach ($keys as $key) {
    $sortedArray[$key] = $array[$key];
}

// Print sorted array by keys
print_r($sortedArray);
?>

Output:

Array
(
    [apple] => 3
    [banana] => 2
    [grape] => 5
    [orange] => 1
)

Explanation:

1. Custom Key Comparison: The customKeyCompare() function uses strcmp() to compare the keys of the array lexicographically (alphabetically).
2. Bubble Sort with Custom Key Comparison: We apply a Bubble Sort algorithm to sort the array’s keys based on our custom comparison function.
3. Rebuilding the Array: After sorting the keys, we rebuild the array in the sorted key order by iterating through the sorted keys and assigning the corresponding values.

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