C Exercises: Multiply two integers without using multiplication, division, bitwise operators, and loops

Last update on March 20 2025 12:36:09 (UTC/GMT +8 hours)

20. Multiply Without Operators & Loops Variants

Write a C program to multiply two integers without using multiplication, division, bitwise operators, and loops.

Example 1:
Input: n1 = 50
Input: n2 = 12
Output: 600
Example 2:
Input: n1 = 0
Input: n2 = 12
Output: 0

Sample Solution:

C Code:

#include <stdio.h>

// Recursive function to multiply two integers 'a' and 'b'
int multiply_two_nums(int a, int b) { 
    /* 0 multiplied with anything gives 0 */
    if (b == 0)
        return 0; // Return 0 if 'b' is zero

    if (b > 0)
        return (a + multiply_two_nums(a, b - 1)); // Recursive call when 'b' is positive, using addition

    if (b < 0)
        return -multiply_two_nums(a, -b); // Recursive call when 'b' is negative, using recursion and negation

    return -1; // Return -1 for invalid inputs
} 

// Main function to test the multiply_two_nums function with different values
int main(void) {
    int n1 = 50;
    int n2 = 12;

    printf("\n %d x %d = %d", n1, n2, multiply_two_nums(n1, n2)); // Print the result of multiplication
    n1 = 0; 
    n2 = 12;

    printf("\n %d x %d = %d", n1, n2, multiply_two_nums(n1, n2)); // Print the result of multiplication

    return 0;    
}

Sample Output:

50 x 12 = 600
 0 x 12 = 0

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to multiply two integers recursively without using multiplication, division, bitwise operators, or loops.
• Write a C program to simulate multiplication by repeated addition implemented via recursion only.
• Write a C program to multiply numbers by breaking the problem into recursive subproblems without loops.
• Write a C program to calculate the product of two integers using a recursive divide-and-conquer strategy without arithmetic operators.

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