高级宏定义

#include<stdio.h>
#define R 6371
#define PI 3.14
#define V PI*R*R*4/3
int main(){
	int r;
	float s;
	printf("输入圆的半径");
	scanf("%d",&r);
//	#undef PI;
	s=PI*r*r;
	printf("%.2f",s);
} 

#include <stdio.h>

#define MAX(x, y) (((x) > (y)) ? (x) : (y))

int main(void)
{
	int x, y;

	scanf("%d%d", &x, &y);
	printf("较大的数%d", MAX(x, y));

	return 0;
}

#include <stdio.h>

#define SQUARE(x) (x * x)

int main(void)
{
	int x;

	scanf("%d", &x);

	printf("%d 的平方 %d\n", x, SQUARE(x));
	printf("%d 的平方 %d\n", x+1, SQUARE(x+1));

	return 0;
}