宏定义一个没有Bug的max函数

#incldue<stdio.h>
#define max(a,b) a>b? a:b

int main(){
	int a = 7;
	printf("%d\n", max(2,3));
	printf("%d\n", 5 + max(2,3));
	printf("%d\n", max(2, max(3, 4)));
	printf("%d\n", max(2, 3>4? 3:4));
	printf("%d\n", max(a++, 6));
}

然而得到的值并不是对的值，不信你试一试
下面给出没有bug的max函数代码

#include<stdio.h>
#define MAX(a,b) ({\
    __typeof(a) __a = (a);\
    __typeof(b) __b = (b);\
    __a > __b ? __a : __b;\
})
#define P(func){\
    printf("%s = %d\n", #func, func);\
}

int main(){

    int a = 7;
    P(MAX(2, 3));
    P(5 + MAX(2, 3));
    P(MAX(2, MAX(3, 4)));
    P(MAX(2, 3>4? 3:4));
    P(MAX(a++, 6));
    return 0;#include<stdio.h>
#define MAX(a,b) ({\
    __typeof(a) __a = (a);\
    __typeof(b) __b = (b);\
    __a > __b ? __a : __b;\
})
#define P(func){\
    printf("%s = %d\n", #func, func);\
}

int main(){

    int a = 7;
    P(MAX(2, 3));
    P(5 + MAX(2, 3));
    P(MAX(2, MAX(3, 4)));
    P(MAX(2, 3>4? 3:4));
    P(MAX(a++, 6));

    return 0;
}