第 15 章 位操作（fields）

 /*-----------------------------------
     fields.c -- 定义并使用字段
 -----------------------------------*/

 #include <stdio.h>

 //线的样式
 #define SOLID    0
 #define DOTTED    1
 #define DASHED    2

 //三原色
 #define BLUE    4
 #define GREEN    2
 #define RED        1

 //混合色
 #define BLACK    (BLUE & GREEN & RED)
 #define YELLOW    (RED | GREEN)
 #define MAGENTA    (RED | BLUE)
 #define CYAN    (GREEN | BLUE)
 #define WHITE    (RED | GREEN | BLUE)

 const char *colors[] =
 {
     "black", "red", "green", "yellow", "blue", "magenta", "cyan", "white"
 };

 struct box_props
 {
     unsigned int opaque : ;
     unsigned int fill_color : ;
     unsigned int : ;
     unsigned int show_border : ;
     unsigned int border_color : ;
     unsigned int border_style : ;
     unsigned int : ;
 };

 void show_settings(const struct box_props *pb);

 int main()
 {
     //创建并初始化 box_props 结构
     struct box_props box = {true, YELLOW, true, GREEN, DASHED};

     printf("Original box settings:\n");
     show_settings(&box);

     box.opaque = false;
     box.fill_color = WHITE;
     box.border_color = MAGENTA;
     box.border_style = SOLID;

     printf("\nModified box settings:\n");
     show_settings(&box);

     return ;
 }

 void show_settings(const struct box_props *pb)
 {
     printf("Box is %s.\n", pb->opaque ? "opaque" : "transparent");

     printf("The fill color is %s.\n", colors[pb->fill_color]);

     printf("Border %s.\n", pb->show_border ? "shown" : "not shown");

     printf("The border color is %s.\n", colors[pb->border_color]);

     printf("The border style is ");
     switch (pb->border_style)
     {
     case SOLID:
         printf("solid.\n");
         break;

     case DOTTED:
         printf("dotted.\n");
         break;

     case DASHED:
         printf("dashed.\n");
         break;

     default:
         printf("unknown type.\n");
         break;
     }
 }

fields.c