Binary to Decimal

import java.util.Scanner;

public class ConvertBinary2Decimal
{
 public static int power(int num ,int pwr)
 {
 int res = 1;
 for (int i = 1; i <= pwr; i++) 
 {
 res = res * num;
 }
 return res;
 }
 public static int B2D(int num)
 {
 int count = 0;
 int output = 0;
 while (num > 0)
 {
 int rem = num % 10;
 output = output+rem*power(2,count++);
 num = num / 10;
 }
 return output;
 }
 public static void main(String[] args)
 {
 Scanner sc = new Scanner(System.in);
 System.out.println("enter the number = ");
 int num = sc.nextInt();
 int res = B2D(num);
 System.out.println("the decimal equivalent of "+num+" = "+res);
 sc.close();
 }

}

Hexadecimal to Decimal Conversion

import java.util.Scanner;

public class ConvertHexa2Decimal
{
 
 public static int power(int num,int pwr)
 {
 int res=1;
 for (int i = 0; i <=pwr; i++) 
 {
 res= res*num;
 }
 return res;
 }
 
 public static int hexToDecimal(String s1)
 {
 int c= s1.length()-1;
 int out=0;
 int count =0;

 while(c>0)
 {
 char ch = s1.charAt(c);
 if(ch>=65 && ch<=70)
 {
 out = out + (ch-55)*power(16, count++);
 }
 else if(ch>=97 && ch<=102)
 {
 out = out + (ch-87)*power(16, count++);
 
 }
 else if(ch>=48 && ch<=57)
 {
 out = out + (ch-48)*power(16, count++);
 
 }
 else
 {
 System.out.println("Invalid character");
 return -1;
 } 
 }
 return out;
 }
  public static void main(String[] args) 
 {
 Scanner sc = new Scanner(System.in);
 System.out.println("Enter the number");
 String s1 = sc.next();
int out = hexToDecimal(s1);
 System.out.println(out);
 sc.close();
 }

}

Strings: Reverse Whole word

import java.util.Scanner;

public class Strings_reverseWholeWord 
{
 public static String reverse(String s1)
 {
 String s2 = "";
 char ch[] = s1.toCharArray();
 for (int i = 0; i < ch.length; i++) 
 {
 String res = "";
 while (i < ch.length && ch[i] != ' ') 
 {
 res = res+ch[i];
 i++;
 }
 s2 =res+" "+s2;
 }
 return s2;
 }

public static void main(String[] args) 
 {
 Scanner sc = new Scanner(System.in);
 System.out.println("Enter the String : ");
 String s1 = sc.nextLine(); 
 System.out.println(reverse(s1));
 sc.close();
 }
 }

Output:

Enter the String :
Welcome to the programming blog
blog programming the to Welcome

Strings: Reverse Each Word

import java.util.Scanner;

public class Strings_reverseEachWord
 {
 public static String reverse(String s1)
 {
 String s2 = "";
 char ch[] = s1.toCharArray();
 for (int i = 0; i < ch.length; i++)
 {
 String res = "";
 while (i < ch.length&& ch[i] != ' ' )
 {
 res = ch[i]+res;
 i++;
 }
 s2 =s2+res+" ";
 }
 return s2;
 }

public static void main(String[] args)
 {
 Scanner sc = new Scanner(System.in);
 System.out.println("Enter the String : ");
 String s1 = sc.nextLine();

String s2 = reverse(s1);
 System.out.println(s2);
 sc.close();
 }
 }

Output:

Enter the String :
welcome to programming blog!! hava a nice day
emoclew ot gnimmargorp !!golb avah a ecin yad