PHP Array Exercises : Function to sort subnets

Last update on May 30 2025 13:14:05 (UTC/GMT +8 hours)

21. Sort Subnets

Write a PHP function to sort subnets.

Sample Solution:

PHP Code:

<?php
// Define a function named 'sort_subnets' for custom sorting of IP subnets
function sort_subnets ($x, $y) {
    // Split IP subnets into arrays of octets
    $x_arr = explode('.', $x);
    $y_arr = explode('.', $y);

    // Iterate through each octet and compare values
    foreach (range(0,3) as $i) {
        // If the current octet in $x is less than the current octet in $y, return -1 (indicating $x comes first)
        if ( $x_arr[$i] < $y_arr[$i] ) {
            return -1;
        }
        // If the current octet in $x is greater than the current octet in $y, return 1 (indicating $y comes first)
        elseif ( $x_arr[$i] > $y_arr[$i] ) {
            return 1;
        }
    }

    // If all octets are equal, return -1 (indicating $x comes first)
    return -1;
}

// Define an array of IP subnets
$subnet_list = array(
    '192.169.12',
    '192.167.11',
    '192.169.14',
    '192.168.13',
    '192.167.12',
    '122.169.15',
    '192.167.16'
);

// Use 'usort' function to sort the array of IP subnets using the 'sort_subnets' custom sorting function
usort($subnet_list, 'sort_subnets');

// Print the sorted array of IP subnets
print_r($subnet_list);
?>

Output:

Array                                                       
(                                                           
    [0] => 122.169.15                                       
    [1] => 192.167.11                                       
    [2] => 192.167.12                                       
    [3] => 192.167.16                                       
    [4] => 192.168.13                                       
    [5] => 192.169.12                                       
    [6] => 192.169.14                                       
)

Flowchart:

For more Practice: Solve these Related Problems:

Write a PHP script to sort an array of subnet addresses numerically by converting each subnet to its decimal equivalent.
Write a PHP function to compare subnet strings and order them based on network address and mask.
Write a PHP program to parse a list of subnet notations, sort them, and then display them in ascending network order.
Write a PHP script to implement a custom sort algorithm that arranges subnets by their starting IP addresses using bitwise operations.

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