C语言：位字段与位运算

#include<stdio.h>
#define YES 1
#define NO 0
#define SOLID 0
#define DOTTED 1
#define DASHED 2
#define  BLUE 4
#define GREEN 2
#define RED 1
#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){
    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");
    }
}

int main(void){
    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;
}

#include<stdio.h>
#define YES 1
#define NO 0
#define SOLID 0
#define DOTTED 1
#define DASHED 2
#define BLUE 4
#define GREEN 2
#define RED 1
#define BLACK 0
#define YELLOW (RED|GREEN)
#define MAGENTA (RED|BLUE)
#define CYAN (GREEN|BLUE)
#define WHITE (RED|GREEN|BLUE)
#define OPAQUE 0x1
#define FILL_BLUE 0x8
#define FILL_GREEN 0x4
#define FILL_RED 0x2
#define FILL_MASK 0xE
#define BORDER 0x100
#define BORDER_BLUE 0x800
#define BORDER_GREEN 0x400
#define BORDER_RED 0x200
#define BORDER_MASK 0xE00
#define B_SOLID 0
#define B_DOTTED 0x1000
#define B_DASHED 0x2000
#define STYLE_MASK 0x3000

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;
};
union Views{
    struct box_props st_view;
    unsigned int ui_view;
};
char* itobs(int n,char* ps){
    int i;
    static int size=8*sizeof(unsigned int);
    for(i=size-1;i>=0;i--,n>>=1){
        ps[i]=(1&n)+'0';
    }
    ps[size]='\0';
    return ps;
}
void show_settings(unsigned short us){
    printf("Box is %s.\n",
        (us&OPAQUE)==OPAQUE?"opaque":"transparent");
    printf("The fill color is %s.\n",colors[(us>>1)&7]);
    printf("Border %s.\n",
        (us&BORDER)==BORDER?"shown":"not shown");
    printf("The border color is %s.\n",colors[(us>>9)&7]);
    printf("The border style is ");
    switch(us&STYLE_MASK){
        case B_SOLID:printf("solid.\n");break;
        case B_DOTTED:printf("dotted.\n");break;
        case B_DASHED:printf("dashed.\n");break;
        default:printf("unknown type.\n");
    }
}

int main(void){
    union Views box={{YES,YELLOW,YES,GREEN,DASHED}};//10010100000111
    char bin_str[8*sizeof(unsigned int)+1];
    printf("Original box settings:\n");
    show_settings(box.ui_view);
    printf("bits are %s\n",itobs(box.ui_view,bin_str));
    box.ui_view&=~FILL_MASK;
    box.ui_view|=(FILL_BLUE|FILL_GREEN);
    box.ui_view^=OPAQUE;
    box.ui_view&=~BORDER_MASK;
    box.ui_view|=(BORDER_RED|BORDER_BLUE);
    box.ui_view&=~STYLE_MASK;
    box.ui_view|=B_DOTTED;
    printf("\nModified box settings:\n");
    show_settings(box.ui_view);
    printf("bits are %s\n",itobs(box.ui_view,bin_str));
    return 0;
}