Write a C program to demonstrate that Interchange Variable Without Using Third Variable.

Here we have a programe for Interchange Variable Without Using Third Variable. First of all, we have to declare two num1, and num2 which is a type of Integer.

int num1,num2;

Then We need to take input from users for num1 and num2. Make sure You don't forget & while Taking Input inside the Scanf statement.

 printf("Enter Value of Number 1:");
 scanf("%d",&num1);
 printf("Enter Value of Number 2:");
 scanf("%d",&num2);

Then we print the values which we inputted from the user by using the print statement. Here we are using %d formate specifier because we are using the Integer dataType.

 printf("Before Swap Numbers are...\n");
 printf("Number 1:%d\nNumber 2:%d",num1,num2);

Here We Have Actual Logic for interchange two variables without using the third variable. for better understand let's take an example. let's assume we have num1=5 and num2=10. now we can add num1 and num2 into num1,so it would be like this num1 = num1 + num2. after doing this, the value of num1 is 15. now, we want to num2 value 5. then we easily do. we just need to do num1 - num2 and it's store in num2 after doing this it will look like this num2 = num1 - num2 so we have value 5 in num2 and that's what we want. now we want value 10 in num1. for as of now we have num1=15 and num2=5. from this value, we can get num1=10.so just do num1 = num1 - num2. and we get num1=10, so this is how you can interchange two variables without using a third variable.

 num1 = num1 + num2; // 15 = 5  +  10
 num2 = num1 - num2; // 10 = 15 -  5
 num1 = num1 - num2; // 5  = 15 -  10

Then we print the values after swap which we take from the user by using the print statement.

 printf("\nAfter Swap Numbers are...\n");
 printf("Number 1:%d\nNumber 2:%d",num1,num2);

Full Code

/**
 Write a C program to demonstrate that Interchange Variable Without
 Using Third Variable.
*/
#include<stdio.h>
int main(){

    int num1,num2;
    printf("Enter Value of Number 1:");
    scanf("%d",&num1);
    printf("Enter Value of Number 2:");
    scanf("%d",&num2);

    printf("Before Swap Numbers are...\n");
    printf("Number 1:%d\nNumber 2:%d",num1,num2);

    num1 = num1 + num2;
    num2 = num1 - num2;
    num1 = num1 - num2;

    printf("\nAfter Swap Numbers are...\n");
    printf("Number 1:%d\nNumber 2:%d",num1,num2);

    return 0;
}

---

OUTPUT

Run 1:

Enter Value of Number 1:-5
Enter Value of Number 2:-10
Before Swap Numbers are...
Number 1:-5
Number 2:-10
After Swap Numbers are...
Number 1:-10
Number 2:-5
Process returned 0 (0x0)   execution time : 6.819 s
Press any key to continue.

---

Run 2:

Enter Value of Number 1:5
Enter Value of Number 2:10
Before Swap Numbers are...
Number 1:5
Number 2:10
After Swap Numbers are...
Number 1:10
Number 2:5
Process returned 0 (0x0)   execution time : 4.618 s
Press any key to continue.