C / C++ / MFC

hr = CoCreateInstance(CLSID_PIAsyncFile, NULL,CLSCTX_INPROC_SERVER, IID_IBaseFilter, (void **)&pAsync);

#include <stdio.h>
int main()
{
    int a, b, add, sub, mul;
    float div;
    char choice='y';
    do {
    printf("Enter any choice:\n1. Addition(a)\n2. Subtraction(b)\n3. Multiplication(c)\n4. Division(d)\n5. Exit(x)");
    scanf("%c", &choice);
    switch(choice)
    {
                  case 'a':
                       {printf("Enter any two numbers:");
                       scanf("%d %d",&a, &b);
                       add = a + b;
                       printf("Sum: %d\n", add);
                       break;}
                  case 'b':
                       printf("Enter any two numbers:");
                       scanf("%d %d",&a, &b);
                       sub = a - b;
                       printf("Difference: %d\n", sub);
                       break;
                  case 'c':
                       printf("Enter any two numbers:");
                       scanf("%d %d",&a, &b);
                       mul = a * b;
                       printf("Product: %d\n", mul);
                       break;
                  case 'd':
                       printf("Enter any two numbers:");
                       scanf("%d %d",&a, &b);
                       div = a / b;
                       printf("Quotient: %f\n", div);
                       break;
                  case 'x':
                       break;
                       }
                       }while(choice!='x');

                  return 0;
                       }