吴裕雄--天生自然C语言开发：位域-优快云博客

本文探讨了C语言中位域与结构体的内存占用情况，通过具体代码示例对比了普通结构体与位域结构体在内存使用上的区别，并展示了位域变量的赋值与读取过程。

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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\n", sizeof(status1));
   printf( "Memory size occupied by status2 : %d\n", 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\n", sizeof(Age) );
   printf( "Age.age : %d\n", Age.age );
 
   Age.age = 7;
   printf( "Age.age : %d\n", Age.age );
 
   Age.age = 8; // 二进制表示为 1000 有四位，超出
   printf( "Age.age : %d\n", Age.age );
 
   return 0;
}