C语言第29天，结构体位段，枚举，联合

结构体位段

#define _CRT_SECURE_NO_WARNINGS

#include<stdio.h>

//结构体位段

struct S {
	int a : 2;
	int b : 5;
	int c : 10;
	int d : 30;
};

int main() {
	struct S s;
	printf("%d\n", sizeof(s));//8 

	return 0;
}

枚举

#define _CRT_SECURE_NO_WARNINGS

#include<stdio.h>

enum Sex {
	//枚举的可能取值
	MALE = 2,
	FEMALE = 4,
	SECRET = 8
};

enum Color {
	RED,
	YELLOW,
	BLUE
};
int main() {
	enum Sex s = MALE;
	enum Color c = BLUE;
	printf("%d %d %d\n", RED, YELLOW, BLUE);//0 1 2
	printf("%d %d %d\n", MALE, FEMALE, SECRET);//2 4 8
	return 0;
}

联合

#define _CRT_SECURE_NO_WARNINGS

#include<stdio.h>

//联合

union Un {
	char c;
	int i;
};

int main() {
	union Un u;
	printf("%d\n", sizeof(u));//4
	printf("%p\n", &u);//00BAFC64
	printf("%p\n", &u.c);//00BAFC64
	printf("%p\n", &u.i);//00BAFC64
	return 0;
}