Frequently Asked Java Program 05: Swap two integer variables without using third variable

Hello Folks,

As part of Frequently Asked Java Programs In Interviews For Freshers And Experienced, in this post we will see a Java program to swap values of two integer variables without using third variable.

Table of Contents

Problem Statement:

Write a java program to swap values of two integer variables without using third variable.

Solution:

It is very commonly asked interview program. In Fact it is less program more mathematics.

Let’s assume there are two variables with some values:

a =10

b=20

2. Now add a and b and store in a:

a = a+b => 10+20 => 30

b= 20

3. Now subtract b from a and store in b:

a= 30

b = a – b => 30-20 => 10

4. Now subtract b from a and store in a:

a= a – b = > 30-10 = > 20

b= 10

5. Notice here that both variables a and b have interchange their values.

Let’s convert above logic into a Java Program.

Java Program:

import java.util.Scanner;

public class SwappingTwoNumbers {

	public static void main(String[] args) {
		
		// taking input from user
		Scanner in = new Scanner(System.in);
		System.out.println("Enter the 1st number: ");
		int x = in.nextInt();
		System.out.println("Enter the 2nd number: ");
		int y = in.nextInt();
		 
		// printing values before swap
		System.out.println("Before Swap: ");
		System.out.println("Value of x: "+x);
		System.out.println("Value of y: "+y);
		
		// swapping without using third variable
		x = x+y;
		y = x-y;
		x = x-y;
		 
		// printing values after swap
		System.out.println("After Swap: ");
		System.out.println("Value of x: "+x);
		System.out.println("Value of y: "+y);
	}
}

import java.util.Scanner;

public class SwappingTwoNumbers {

public static void main(String[] args) {

// taking input from user

Scanner in = new Scanner(System.in);

System.out.println("Enter the 1st number: ");

int x = in.nextInt();

System.out.println("Enter the 2nd number: ");

int y = in.nextInt();

// printing values before swap

System.out.println("Before Swap: ");

System.out.println("Value of x: "+x);

System.out.println("Value of y: "+y);

// swapping without using third variable

x = x+y;

y = x-y;

x = x-y;

// printing values after swap

System.out.println("After Swap: ");

System.out.println("Value of x: "+x);

System.out.println("Value of y: "+y);

}

Output:

[java]
Enter the 1st number:
21
Enter the 2nd number:
33
Before Swap:
Value of x: 21
Value of y: 33
After Swap:
Value of x: 33
Value of y: 21
[/java]

[java]

Enter the 1st number:

Enter the 2nd number:

Before Swap:

Value of x: 21

Value of y: 33

After Swap:

Value of x: 33

Value of y: 21

[/java]

#HappyCoding

Author: Amod Mahajan

A software Tester who is paid to judge products developed by others. Currently getting paid in American Dollars. Writing technical posts and creating YouTube videos are my hobbies.

3 thoughts on “Frequently Asked Java Program 05: Swap two integer variables without using third variable”

Cecil Tom says:

June 14, 2021 at 10:55 pm

Try with XOR option too as + may result in overflow –
a=a^b ; ( a XOR B)
b=a^b; ( a XOR B)
a=a^b; ( a XOR B)

=====================

1 XOR 0 = 1
0 XOR 1= 1
0 XOR 0 = 0
1 XOR 1 =0

Sathiyasheelan says:

December 15, 2019 at 5:35 pm

Good work

RANJAN V says:

June 20, 2017 at 6:15 pm

Nice..)))

Frequently Asked Java Program 05: Swap two integer variables without using third variable

Problem Statement:

Solution:

Java Program:

Author: Amod Mahajan

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3 thoughts on “Frequently Asked Java Program 05: Swap two integer variables without using third variable”

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