Tutorial on swapping two numbers

 Swapping 2 integers with temporary variable

Swapping Technique:

If there are two variables with some integer values and needed to swap variable a's value in variable b and b's value to a

Swapping two integers with temporary variable is as easy 10 lines of code. It does not include any mathematical operations.

Example:

If variable a has value 10 and variable b has value 20, the algorithm, supposed to swap values in such a way, that variable a will have value 20 and variable b will have 10.

int a = 10; // variable a has 10 as a value

int b = 20; // variable b has 20 as a value

Code

package com.allabtjava.alg;

/**

* @author Nagasharath K

*/

public class Swap_With_Temp {

public static void main(String[] args) {

int a = 10;

int b = 20;

System.out.println("Variable a has " + a + "and b has " + b + "before swapping");

int temp = 0;

temp = a;

a = b;

b = temp;

System.out.println("After swapping variable a has " + a + " and b has " + b);

}

}

Output:

Variable a has 10 and b has 20 before swapping

After swapping variable a has 20 and b has 10

Swapping 2 integers without temporary variable

Now, let us swap 2 integers without the help of temporary variable. 

This is possible by storing the difference between variable a and variable b and do the simple

mathematical operation as done in the below program

Example:

package com.allabtjava.alg;

 /**

 * @author NAGASHARATH K 

 */

 public class Swap_Without_Temp { 

 public static void main(String[] args) {

    int a = 70;

    int b = 50;

   System.out.println("Variable a has " + a + " and b has " + b + " before swapping");

   int c = b - a;

   a = a + c;

   b = b - c;

   System.out.println("After swapping variable a has " + a + " and b has " + b);

   }

} 

Output:

 Variable a has 70and b has 50 before swapping

 After swapping variable a has 50 and b has 70