吴裕雄--天生自然C语言开发：位域

struct
{
  unsigned int widthValidated;
  unsigned int heightValidated;
} status;

struct
{
  unsigned int widthValidated : 1;
  unsigned int heightValidated : 1;
} status;

#include <stdio.h>
#include <string.h>
 
/* 定义简单的结构 */
struct
{
  unsigned int widthValidated;
  unsigned int heightValidated;
} status1;
 
/* 定义位域结构 */
struct
{
  unsigned int widthValidated : 1;
  unsigned int heightValidated : 1;
} status2;
 
int main( )
{
   printf( "Memory size occupied by status1 : %d
", sizeof(status1));
   printf( "Memory size occupied by status2 : %d
", sizeof(status2));
 
   return 0;
}

struct
{
  unsigned int age : 3;
} Age;

#include <stdio.h>
#include <string.h>
 
struct
{
  unsigned int age : 3;
} Age;
 
int main( )
{
   Age.age = 4;
   printf( "Sizeof( Age ) : %d
", sizeof(Age) );
   printf( "Age.age : %d
", Age.age );
 
   Age.age = 7;
   printf( "Age.age : %d
", Age.age );
 
   Age.age = 8; // 二进制表示为 1000 有四位，超出
   printf( "Age.age : %d
", Age.age );
 
   return 0;
}