mutiplication_a_la_russe.c

/* multiplication_a_la_russe.c
 * multiplication a la russé 
 */

#include <stdio.h>

int main()
{
  int op1, op2, total_sum = 0;

  printf("Enter two integers: ");
  scanf("%d %d", &op1, &op2);

  printf("-------------------\n");

  while (op1 >= 1) {
    printf("%d \t %d \t", op1, op2);

    if ( op1 % 2 == 0 ) {
      printf("---\n"); 
    } else {
      printf("%d \n", op2); 
      total_sum += op2;
    }

    // halve op1, double op2
    op1 >>= 1;
    op2 <<= 1;
  
  }

  printf("Final Product:  %d \n", total_sum);
  
  return 0;
}

More information on the algorithm here: http://mathworld.wolfram.com/RussianMultiplication.html

• c int main(void) non void fn's are implicitly int.
• c if (op1 % 2 == 0)... can be c if (!(op1 % 2)) as anything not zero is true.