c primer plus 第五版的书上源码

				/* fields.c -- define and use fields */
				#include 
				/* opaque and show */
				#define YES     1
				#define NO      0
				/* line styles     */
				#define SOLID   0
				#define DOTTED  1
				#define DASHED  2
				/* primary colors  */
				#define BLUE    4
				#define GREEN   2
				#define RED     1
				/* mixed colors    */
				#define BLACK   0
				#define YELLOW  (RED | GREEN)
				#define MAGENTA (RED | BLUE)
				#define CYAN    (GREEN | BLUE)
				#define WHITE   (RED | GREEN | BLUE)
				
				const char * colors[8] = {"black", "red", "green", "yellow",
				            "blue", "magenta", "cyan", "white"};
				            
				struct box_props {
				    unsigned int opaque         : 1;
				    unsigned int fill_color     : 3;
				    unsigned int                : 4;
				    unsigned int show_border    : 1;
				    unsigned int border_color   : 3;
				    unsigned int border_style   : 2;
				    unsigned int                : 2;
				};
				 
				void show_settings(const struct box_props * pb);
				
				int main(void)
				{
				    /* create and initialize box_props structure */
				    struct box_props box = {YES, YELLOW , YES, GREEN, DASHED};
				
				    printf("Original box settings:\n");
				    show_settings(&box);
				    
				    box.opaque = NO; 
				    box.fill_color = WHITE;
				    box.border_color = MAGENTA;
				    box.border_style = SOLID;
				    printf("\nModified box settings:\n");
				    show_settings(&box);
				  
				    return 0;
				}
				
				void show_settings(const struct box_props * pb)
				{
				    printf("Box is %s.\n",
				            pb->opaque == YES? "opaque": "transparent");
				    printf("The fill color is %s.\n", colors[pb->fill_color]);
				    printf("Border %s.\n",
				            pb->show_border == YES? "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");
				    }
				}