C Program To Add Two Numbers without using Plus Operator

Lets write a C program to perform addition of 2 numbers without using plus symbol or the addition operator(+).

In this video tutorial we are using ~(tilde symbol) bitwise complement operator to perform the operation to get to the anticipated result.

Example: If user enters 2 numbers. a = 8 and b = 7. To add 8 and 7 we use result = a + b. And the result will be 15. But in this C program we are not using plus(+) operation, but still we must get the same result 15(for above input).

Logic To Add Two Numbers without using Plus Operator

If num = 7;
result = ~num; will give 1s complement of 7, that is -8.
result = -(~num); will give 8.
result = -(~num)-1; will give 7.

Now using this logic, we ask the user to enter 2 numbers. If user enters a = 8 and b = 7. We use the below logic to perform addition, without using plus symbol:

a = 8, b = 7;
add = a – ~b – 1;
add = 8 – (-8) – 1;
add = 8 + 8 – 1;
add = 8 + 7;
add = 15;

This would give proper required result.

Source Code: C Program To Add Two Numbers without using Plus Operator

#include < stdio.h >

int main()
{
    int a, b, add;

    printf("Enter 2 numbers for addition\n");
    scanf("%d%d", &a, &b);

    add = a-~b-1; 

    printf("Addition of %d and %d is %d\n", a, b, add);

    return 0;
}

Output 1:
Enter 2 numbers for addition
1
2
Addition of 1 and 2 is 3

Output 2:
Enter 2 numbers for addition
-1
2
Addition of -1 and 2 is 1

Output 3:
Enter 2 numbers for addition
-1
-2
Addition of -1 and -2 is -3

Output 4:
Enter 2 numbers for addition
-5
5
Addition of -5 and 5 is 0

Output 5:
Enter 2 numbers for addition
5
-10
Addition of 5 and -10 is -5

Video Tutorial: C Program To Add Two Numbers without using Plus Operator

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