求问，为什么运行后num1和num2都等于2且Ret=4

Question

#include
int ObserveArgument(int num1,int num2)
{
printf("num1=%d\tnum2=%d\n",num1,num2);
return(num1+num2);
}
int main()
{
int i=3;
printf("i=%d\tRet=%d\n",i,ObserveArgument(i++,--i));
}

Answer 1

i=3 num1+num2 = 1