typedef

宏在预处理时解释

typedef在编译时解释

用法一：定义函数指针

#ifdef TYPEDEF_TEST
typedef int (*get_num_func)(int);
get_num_func get_num;
#else
int (*get_num)(int);
#endif

int my_get_num(int num)
{
    return num;
}

int main()
{
    get_num = my_get_num;
    (*get_num)(0);

    return 0;
}

用法二：定义变量类型别名

typedef unsigned int guint;

typedef struct student{
char *name;
char *id;
}student_t;