ass3subnet

import java.util.Scanner;

class ass3subnet {
    public static void main(String args[]) {
        try (Scanner sc = new Scanner(System.in)) {
            System.out.print("Enter the ip address: ");
            String ip = sc.nextLine();
            String split_ip[] = ip.split("\\.");
            String split_bip[] = new String[4]; // split binary ip
            String bip = "";
            for (int i = 0; i < 4; i++) {
                split_bip[i] = appendZeros(Integer.toBinaryString(Integer.parseInt(split_ip[i])));
                bip += split_bip[i];
            }
            System.out.println("IP in binary is " + bip);
            System.out.print("Enter the number of addresses: ");
            int n = sc.nextInt();
            // Calculation of mask
            int bits = (int) Math.ceil(Math.log(n) / Math.log(2));
            System.out.println("Number of bits required for address = " + bits);
            int mask = 32 - bits;
            System.out.println("The subnet mask is = " + mask);
            // Calculation of first address and last address
            int fbip[] = new int[32];
            for (int i = 0; i < 32; i++)
                fbip[i] = (int) bip.charAt(i) - 48;
            for (int i = 31; i > 31 - bits; i--)
                fbip[i] &= 0;
            String fip[] = { "", "", "", "" };
            for (int i = 0; i < 32; i++)
                fip[i / 8] = new String(fip[i / 8] + fbip[i]);
            System.out.print("Subnet address is = ");
            for (int i = 0; i < 4; i++) {
                System.out.print(Integer.parseInt(fip[i], 2));
                if (i != 3)
                    System.out.print(".");
            }
            System.out.println();
            int lbip[] = new int[32];
            for (int i = 0; i < 32; i++)
                lbip[i] = (int) bip.charAt(i) - 48;
            for (int i = 31; i > 31 - bits; i--)// Get last address by ORing last n bits with 1
                lbip[i] |= 1;
            String lip[] = { "", "", "", "" };
            for (int i = 0; i < 32; i++)
                lip[i / 8] = new String(lip[i / 8] + lbip[i]);
            System.out.print("Broadcast address is = ");
            for (int i = 0; i < 4; i++) {
                System.out.print(Integer.parseInt(lip[i], 2));
                if (i != 3)
                    System.out.print(".");
            }
        } catch (NumberFormatException e) {
            e.printStackTrace();
        }
        System.out.println();
    }

    static String appendZeros(String s) {
        String temp = new String("00000000");
        return temp.substring(s.length()) + s;
    }
}