#include <stdio.h>

int main() {
    int num, sum = 0;

    printf("Enter a number: ");
    scanf("%d", &num);

    // Calculate sum of digits
    while (num != 0) {
        sum += num % 10;
        num = num / 10;
    }

    printf("Sum of digits = %d\n", sum);

    return 0;
}

a) Full form:
DHCP = Dynamic Host Configuration Protocol
ARP = Address Resolution Protocol

b) For IP 192.168.10.100/26

(i) Network address:
/26 subnet mask = 255.255.255.192
Block size = 64
Subnets are: 0, 64, 128, 192
100 falls in 64–127
So, Network address = 192.168.10.64

(ii) Maximum number of hosts:
Host bits = 32 − 26 = 6
Total IPs = 2⁶ = 64
Usable hosts = 64 − 2 = 62

(iii) Broadcast address of IP 9.1.5.31 with default subnet mask 250.0.0.0:
250.0.0.0 is not a valid subnet mask, so the broadcast address cannot be determined using that mask.

If the question intended the default Class A mask, then it should be 255.0.0.0.
In that case:
Network address = 9.0.0.0
Broadcast address = 9.255.255.255

Final answers:
DHCP = Dynamic Host Configuration Protocol
ARP = Address Resolution Protocol
Network address = 192.168.10.64
Maximum number of hosts = 62
Broadcast address for 9.1.5.31 with mask 250.0.0.0 = invalid question
If mask is 255.0.0.0, then broadcast = 9.255.255.255

<?php
// Database connection parameters
$hostname = "localhost";
$db_username = "root";
$db_password = "";
$database = "test_db";

// Create connection
$conn = new mysqli($hostname, $db_username, $db_password, $database);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// Get login data from form
$username = $_POST['username'];
$password = $_POST['password'];

// SQL query to check user
$sql = "SELECT * FROM users WHERE username='$username' AND password='$password'";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    echo "Login Successful";
} else {
    echo "Invalid Username or Password";
}

$conn->close();
?>