目录

• 联合体的定义
• 联合体的大小
• 联合体变量的定义
• 联合体变量的初始化
• 联合体变量的访问和赋值

联合体的定义

union 联合体名
{
	数据类型 成员1；
	数据类型 成员2；
	...
};

union A
{
	char a;
	int b;
	double c;
};

联合体的大小

printf("Size of the union A: %u bytes.\n",sizeof(union A));//关键字union不能省略掉

Size of the union A: 8 bytes.

联合体变量的定义

union A a1;

union A
{
	char a;
	int b;
	double c;
}a2;

union
{
	char a;
	int b;
	double c;
}a3;

联合体变量的初始化

union A a1 = {'A'};

union A a1 = {'A',35};

union A a1 = {.b = 35};

union A a2 = a1;

联合体变量的访问和赋值

union A a1 = {'A'};
printf("Member a: %c\n",a1.a);

Member a: A

a1.b = 100;

printf("Member a: %d\n",a1.b");

Member a: 100

printf("Member a: %c\n",a1.a);

Member a: d

union A a2;
a2 = a1;

#include <stdio.h>
union IP
{
	unsigned char str[4];
	unsigned int digit;
};
int main()
{
	union IP ip;
	printf("Please enter IP address in string format:\n");
	scanf("%d.%d.%d.%d",&ip.str[0],&ip.str[1],&ip.str[2],&ip.str[3]);
	printf("IP address in digital format is: %u\n",ip.digit);
	return 0;
}

Please enter IP address in string format:
192.168.101.120
IP address in digital format is: 2019928256