C program to multiply two numbers using bitwise operator

Write a C program to multiply two numbers using bitwise operator.

Please check the below link to get better understanding on this program.

• Add to numbers using bitwise operators.

  #include <stdio.h>

  /* bitwiseAdd of two numbers without using addition operator */
  int bitwiseAdd(int a, int b) {
        int carry;
        while (b != 0) {
                /* calculating the carry and do a left shift*/
                carry = (a & b) << 1;
                /* calculating the sum */
                a = a ^ b;
                b = carry;
        }
        return a;
  }

  int main () {
        int val1, val2, output = 0, i;
        /* get the input from the user */
        printf ("Enter your first input:");
        scanf("%d", &val1);
        printf("Enter your second input:");
        scanf("%d", &val2);

        /*
         * Adding val1 for val2 times gives the product
         * value.  Product of two numbers without using
         * arithmetic operator.
         */
        for (i = 0; i < val2; i++) {
                output = bitwiseAdd(output, val1);
        }

        printf("product of %d and %d is %d\n", val1, val2, output);
        return 0;
  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your first input:55
  Enter your second input:11
  product of 55 and 11 is 605