#include <stdio.h> 

int main() {
  int varA = 6;
  int varB = 7;
  __asm {
    //add varA, varB      ; // does not work
    mov eax, varB         ; // this works instead:
    add varA, eax         ; //
  }
  printf("varA = %d\n", varA);

  __asm {
    mov eax, 21         
    mov edx, 24
    add eax, edx
    mov varA, eax
  }

  printf("varA = %d\n", varA);

  return 0;
}