C语言编程：#if #ifdef和#ifndef的综合应用

问题描述：#if #ifdef和#ifndef的综合应用。

程序源码：

#include<stdio.h>
#define MAX
#define MAXIMUM(x,y) (x>y)?x:y
#define MINIMUM(x,y) (x>y)?y:x
void main()
{ 
int a=10,b=20;
#ifdef MAX
printf("\40: The larger one is %d\n",MAXIMUM(a,b));
#else
printf("\40: The lower one is %d\n",MINIMUM(a,b));
#endif
#ifndef MIN
printf("\40: The lower one is %d\n",MINIMUM(a,b));
#else
printf("\40: The larger one is %d\n",MAXIMUM(a,b));
#endif
#undef MAX
#ifdef MAX
printf("\40: The larger one is %d\n",MAXIMUM(a,b));
#else
printf("\40: The lower one is %d\n",MINIMUM(a,b));
#endif
#define MIN
#ifndef MIN
printf("\40: The lower one is %d\n",MINIMUM(a,b));
#else
printf("\40: The larger one is %d\n",MAXIMUM(a,b));
#endif
}