C Exercises: Multiply two numbers using bitwise operators

Last update on March 20 2025 12:35:30 (UTC/GMT +8 hours)

27. Multiply Using Bitwise Operators Variants

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

Example:
Input: int x = 8
         int y = 9
Output: Product of 8 and 9 using bitwise operators is: 72

Sample Solution:

C Code:

#include <stdio.h>
#include <math.h>

// Function to perform multiplication using bitwise operators
int bitwise_multiply(int x, int y) {
    // Adjust signs if both x and y are negative or if y is negative
    if (x < 0 && y < 0) {
        x = x * (-1);
        y = y * (-1);
    } else if (x > 0 && y < 0) {
        x = x * (-1);
        y = y * (-1);
    }

    int result = 0; // Initialize the result variable to store the product

    // Multiply using bitwise operations
    while (y > 0) {
        if ((y & 1) != 0) // If the least significant bit of y is set
            result = result + x; // Add x to the result
        x = x << 1; // Left shift x to multiply it by 2
        y = y >> 1; // Right shift y to divide it by 2
    }

    return result; // Return the final product
}

int main(void) {
    int x = 8; // First number for multiplication
    int y = 9; // Second number for multiplication

    // Print the product of x and y calculated using bitwise operators
    printf("Product of %d and %d using bitwise operators is: %d", x, y, bitwise_multiply(x, y));

    return 0; // End of the main function
}

Sample Output:

Product of 8 and 9 using bitwise operators is: 72

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to multiply two numbers using only bitwise operators and addition.
• Write a C program to simulate multiplication by shifting and adding, without using arithmetic operators.
• Write a C program to implement a bitwise multiplication algorithm and test it with both positive and negative numbers.
• Write a C program to multiply two integers using bitwise left shifts for doubling and recursive addition.

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