Program to Find Class From Binary IP Address Classful Addressing

An IP address is an important concept in computers and networking. IP address helps each packet which uses routing tables to determine the best route for the packet to take to reach its destination. That makes the Class of an IP address an important concept so let us check how to find a class from a Binary IP address.

Representation of addresses in classful addressing can specifically be in 2 types as follows:

1. Binary notation 
2. Dotted-decimal notation

Recognizing classes

We can find the classes of an address when the address is given either in binary or dotted-decimal notation. In binary notation, the first few bits can immediately tell us the class of the address; in dotted-decimal notation, the value of the first byte can give the class of an address as shown below figure.

Different classes of Internet Protocol

Steps to find the class is defined below:

1. As we know from the above figure the first octet determines the class in classful addressing, we will consider the first 8 bits.
2. check the first bit if it is 0 then class A.
3. If not check the second bit if it is 0 then class B.
4. If the first bit is 1 & the second bit is 1 and the third bit is 0 then the class is C.
5. If all the first 3 bits are 1 and the fourth bit is o then class D.
6. If all the first bits are 1 then class E.

Example:

C

// C Program to find class from
// Binary IP  address classful addressing.
#include <stdio.h>
#include <string.h>

// Driver Code
int main()
{
    // IP declared IPv4
    // 11100110.00110100.01101010.11010100
    int s[32] = { 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1,
                  1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0,
                  1, 0, 1, 1, 0, 1, 0, 1, 0, 0 };

    // Checking on all characters
    for (int i = 0; i < 32; i++) {
        if (!(s[i] == 0 || s[i] == 1)) {
            printf("Invalid");
            break;
        }

        if (i != 0 && i % 8 == 0)
            printf(" ");

        printf("%d", s[i]);
    }

    // Condition for Class A
    if (s[0] == 0) {
        printf("\nClass A");
    }

    // Condition for Class B
    else if (s[0] == 1 && s[1] == 0) {
        printf("\nClass B");
    }

    // Condition for Class C
    else if (s[0] == 1 && s[1] == 1 && s[2] == 0) {
        printf("\nClass C");
    }

    // Condition for Class D
    else if (s[0] == 1 && s[1] == 1 && s[2] == 1
             && s[3] == 0) {
        printf("\nClass D ");
    }

    // Condition for Class E
    else {
        printf("\nClass E");
    }

    return 0;
}

C++

// C++ Program to find class from
// Binary IP  address classful addressing.
#include <iostream>
using namespace std;

// Driver Code
int main()
{
    // IP declared IPv4
    // 11100110.00110100.01101010.11010100
    int s[32] = { 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1,
                  1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0,
                  1, 0, 1, 1, 0, 1, 0, 1, 0, 0 };


    // Checking on all characters
    for (int i = 0; i < 32; i++) {
        if (!(s[i] == 0 || s[i] == 1)) {
            cout << "Invalid";
            break;
        }

        if (i != 0 && i % 8 == 0)
            cout << " ";

        cout << s[i];
    }

      cout<<endl;

    // Condition for Class A
    if (s[0] == 0) {
        cout << "Class A";
    }

    // Condition for Class B
    else if (s[0] == 1 && s[1] == 0) {
        cout << "Class B";
    }

    // Condition for Class C
    else if (s[0] == 1 && s[1] == 1 && s[2] == 0) {
        cout << "Class C";
    }

    // Condition for Class D
    else if (s[0] == 1 && s[1] == 1 && s[2] == 1
             && s[3] == 0) {
        cout << "Class D";
    }

    // Condition for Class E
    else {
        cout << "Class E";
    }

    return 0;
}

Java

/*package whatever //do not write package name here */
import java.util.Scanner;

public class Main {
  public static void main(String[] args) {
    // IP declared IPv4
    // 11100110.00110100.01101010.11010100
    int[] s = new int[]{1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1,
        1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0,
        1, 0, 1, 1, 0, 1, 0, 1, 0, 0};

    // Checking on all characters
    for (int i = 0; i < 32; i++) {
      if (!(s[i] == 0 || s[i] == 1)) {
        System.out.println("Invalid");
        break;
      }

      if (i != 0 && i % 8 == 0) {
        System.out.print(" ");
      }

      System.out.print(s[i]);
    }

    // Condition for Class A
    if (s[0] == 0) {
      System.out.println("\nClass A");
    }

    // Condition for Class B
    else if (s[0] == 1 && s[1] == 0) {
      System.out.println("\nClass B");
    }

    // Condition for Class C
    else if (s[0] == 1 && s[1] == 1 && s[2] == 0) {
      System.out.println("\nClass C");
    }

    // Condition for Class D
    else if (s[0] == 1 && s[1] == 1 && s[2] == 1
        && s[3] == 0) {
      System.out.println("\nClass D");
    }

    // Condition for Class E
    else {
      System.out.println("\nClass E");
    }
  }
}

Python

s = [1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1,
     1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0,
     1, 0, 1, 1, 0, 1, 0, 1, 0, 0]

# Checking on all characters
for i in range(32):
    if s[i] != 0 and s[i] != 1:
        print("Invalid")
        break

    if i != 0 and i % 8 == 0:
        print(" ")

    print(s[i])

# Condition for Class A
if s[0] == 0:
    print("\nClass A")

# Condition for Class B
elif s[0] == 1 and s[1] == 0:
    print("\nClass B")

# Condition for Class C
elif s[0] == 1 and s[1] == 1 and s[2] == 0:
    print("\nClass C")

# Condition for Class D
elif s[0] == 1 and s[1] == 1 and s[2] == 1 and s[3] == 0:
    print("\nClass D")

# Condition for Class E
else:
    print("\nClass E")

C#

using System;

class MainClass {
    public static void Main(string[] args)
    {
        // IP declared IPv4
        // 11100110.00110100.01101010.11010100
        int[] s
            = new int[] { 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1,
                          1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0,
                          1, 0, 1, 1, 0, 1, 0, 1, 0, 0 };

        // Checking on all characters
        for (int i = 0; i < 32; i++) {
            if (!(s[i] == 0 || s[i] == 1)) {
                Console.WriteLine("Invalid");
                break;
            }

            if (i != 0 && i % 8 == 0) {
                Console.Write(" ");
            }

            Console.Write(s[i]);
        }

        // Condition for Class A
        if (s[0] == 0) {
            Console.WriteLine("\nClass A");
        }

        // Condition for Class B
        else if (s[0] == 1 && s[1] == 0) {
            Console.WriteLine("\nClass B");
        }

        // Condition for Class C
        else if (s[0] == 1 && s[1] == 1 && s[2] == 0) {
            Console.WriteLine("\nClass C");
        }

        // Condition for Class D
        else if (s[0] == 1 && s[1] == 1 && s[2] == 1
                 && s[3] == 0) {
            Console.WriteLine("\nClass D");
        }

        // Condition for Class E
        else {
            Console.WriteLine("\nClass E");
        }
    }
}
// This code is contributed by Prajwal Kandekar

Javascript

// Javascript Equivalent
// IP declared IPv4
// 11100110.00110100.01101010.11010100
const s = [1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 0];
temp="";
// Checking on all characters
for (let i = 0; i < 32; i++) {
  if (!(s[i] === 0 || s[i] === 1)) {
    console.log("Invalid");
    break;
  }

  if (i !== 0 && i % 8 === 0) {
    temp=temp+" ";
  }

  temp = temp +s[i] + "";
}
console.log(temp);
// Condition for Class A
if (s[0] === 0) {
  console.log("\nClass A");
}

// Condition for Class B
else if (s[0] === 1 && s[1] === 0) {
  console.log("\nClass B");
}

// Condition for Class C
else if (s[0] === 1 && s[1] === 1 && s[2] === 0) {
  console.log("\nClass C");
}

// Condition for Class D
else if (s[0] === 1 && s[1] === 1 && s[2] === 1 && s[3] === 0) {
  console.log("\nClass D");
}

// Condition for Class E
else {
  console.log("\nClass E");
}

Output

11100110 00110100 01101010 11010100
Class D 

Time Complexity: O(32). 

Space Complexity: O(1) as no extra space has been used except input array.