Swapping two numbers without using temporary variable

Very basic interview question : Swap two variables without using third or temporary variables.  This serves the purpose of getting started with the interview. There are 3 ways to do this and we will discus all of them now

1. Addition
2. XOR operation(bitwise operator)
3. Multiplication

By Addition

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/**    * Created with IntelliJ IDEA.  * User: aniket  * Date: 19/12/13  * Time: 8:20 PM  */ public class VariableSwapper {     public static void main(String args[]){         int a = 4;         int b = 5;         System.out.println("***** Swapping using Addition *****");         System.out.println("Before Swapping a : " + a);         System.out.println("Before Swapping b : " + b);         a = a + b;         b = a - b;         a = a - b;         System.out.println("After Swapping a : " + a);         System.out.println("After Swapping b : " + b);     }   }

By XOR operation

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/**  * Created with IntelliJ IDEA.  * User: aniket  * Date: 19/12/13  * Time: 8:20 PM  */ public class VariableSwapper {       public static void main(String args[]){           int a = 4;         int b = 5;         System.out.println("***** Swapping using XOR *****");         System.out.println("Before Swapping a : " + a);         System.out.println("Before Swapping b : " + b);         a = a ^ b;         b = a ^ b;         a = a ^ b;         System.out.println("After Swapping a : " + a);         System.out.println("After Swapping b : " + b);       }   }

By Multiplication

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/**  * Created with IntelliJ IDEA.  * User: aniket  * Date: 19/12/13  * Time: 8:20 PM  */ public class VariableSwapper {       public static void main(String args[]){           int a = 4;         int b = 5;           System.out.println("***** Swapping using Multiplication *****");           System.out.println("Before Swapping a : " + a);         System.out.println("Before Swapping b : " + b);           a = a * b;         b = a / b;         a = a / b;           System.out.println("After Swapping a : " + a);         System.out.println("After Swapping b : " + b);       }   }

Output remains the same except printing the method part.

***** Swapping using Multiplication *****
Before Swapping a : 4
Before Swapping b : 5
After Swapping a : 5
After Swapping b : 4 

XOR logic can be better understood with following diagram