EXP 8

// C program to determine class, Network
// and Host ID of an IPv4 address
#include<stdio.h>
#include<string.h>

// Function to find out the Class
char findClass(char str[])
{
    // storing first octet in arr[] variable
    char arr[4];
    int i = 0;
       int ip = 0, j = 1;
    while (str[i] != '.')
    {
arr[i] = str[i];
i++;
    }
    i--;

    // converting str[] variable into number for
    // comparison

    while (i >= 0)
    {
ip = ip + (str[i] - '0') * j;
j = j * 10;
i--;
    }

    // Class A
    if (ip >=1 && ip <= 126)
return 'A';

    // Class B
    else if (ip >= 128 && ip <= 191)
return 'B';

    // Class C
    else if (ip >= 192 && ip <= 223)
return 'C';

    // Class D
    else if (ip >= 224 && ip <= 239)
return 'D';

    // Class E
    else
return 'E';
}

// Function to separate Network ID as well as
// Host ID and print them
void separate(char str[], char ipClass)
{
    // Initializing network and host array to NULL
    char network[12], host[12];
    int k;
    for ( k = 0; k < 12; k++)
network[k] = host[k] = '\0';

    // for class A, only first octet is Network ID
    // and rest are Host ID
    if (ipClass == 'A')
    {
int i = 0, j = 0;
while (str[j] != '.')
    network[i++] = str[j++];
i = 0;
j++;
while (str[j] != '\0')
    host[i++] = str[j++];
printf("Network ID is %s\n", network);
printf("Host ID is %s\n", host);
    }

    // for class B, first two octet are Network ID
    // and rest are Host ID
    else if (ipClass == 'B')
    {
int i = 0, j = 0, dotCount = 0;

// storing in network[] up to 2nd dot
// dotCount keeps track of number of
// dots or octets passed
while (dotCount < 2)
{
    network[i++] = str[j++];
    if (str[j] == '.')
dotCount++;
}
i = 0;
j++;

while (str[j] != '\0')
    host[i++] = str[j++];

printf("Network ID is %s\n", network);
printf("Host ID is %s\n", host);
    }

    // for class C, first three octet are Network ID
    // and rest are Host ID
    else if (ipClass == 'C')
    {
int i = 0, j = 0, dotCount = 0;

// storing in network[] up to 3rd dot
// dotCount keeps track of number of
// dots or octets passed
while (dotCount < 3)
{
    network[i++] = str[j++];
    if (str[j] == '.')
dotCount++;
}

i = 0;
j++;

while (str[j] != '\0')
    host[i++] = str[j++];

printf("Network ID is %s\n", network);
printf("Host ID is %s\n", host);
    }

    // Class D and E are not divided in Network
    // and Host ID
    else
printf("In this Class, IP address is not"
   " divided into Network and Host ID\n");
}

// Driver function is to test above function
int main()
{
    char str[] = "124.226.12.11";
    char ipClass = findClass(str);
    clrscr();
    printf("Given IP address belongs to Class %c\n",
   ipClass);
    separate(str, ipClass);
    getch();
    return 0;
}

/*

output
Given IP address belongs to Class A
Network ID is 124
Host ID is 226.12.11
*/