c primer plus第15章 位操作

#include <stdio.h>

#define YES 1
#define NO  0

#define SOLID  0
#define DOTTED 1 //有点的
#define DASHED 2 //虚线

#define BULE   4
#define GREEN  2
#define RED    1

#define BLACK  0
#define YELLOW (RED | GREEN)
#define MAGENTA (RED | BULE)
#define CYAN (GREEN | BLUE)
#define WHITE (RED | GREEN | BULE)

#define OPAQUE 0x1
#define FILL_BLUE 0x8
//#define FILL_BLUE 1<<3
#define FILL_GREEN 0x4
//#define FILL_GREEN 1<<2

#define FILL_RED 0x2
#define FILL_MASK 0xE
#define BORDER 0x100
#define BORDER_BLUE 0x800
//#define BORDER_BLUE 1<<11
#define BORDER_GREEN 0x400
#define BORDER_RED 0x200
//define BORDER_RED 0010 0000 0000
#define BORDER_MASK 0xE00
#define B_SOLID 0
#define B_DOTTED 0x1000
//#define B_DOTTED 0001 0000 0000 0000
#define B_DASHED 0x2000
#define STYLE_MASK 0x3000
//#define STYLE_MASK 0011 0000 0000 0000

const char * colors[8] = { "black", "red", "green", "yellow", "blue", "magenta",
        "cyan", "white" };

struct box_props {
    unsigned int opaque       : 1;//1
    unsigned int fill_color   : 3;//011
    unsigned int              : 4;//0000
    unsigned int show_border  : 1;//1
    unsigned int border_color : 3;//010
    unsigned int border_style : 2;//010
    unsigned int              : 2;//00
    //               00010010100000111
    //00000000000000000010010100000111
};

union Views
{
    struct box_props st_view;
    unsigned int ui_view;
};

void show_settings(const struct box_props * pb);
void show_settings1(unsigned short us);
char * itobs(int n, char * ps);

//0-9对应0-9;A-F对应10-15
//0 1 2 3 4 5 6 7 8 9 A B C D E F

int main(void)
{
    union Views box = {YES, YELLOW, YES, GREEN, DASHED};
    char bin_str[8 * sizeof(unsigned int) + 1];

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

    printf("\nBox settings using unsigned int view:\n");
    show_settings1(box.ui_view);

    //00000000000000000010010100000111
printf("bits are %s\n", itobs(box.ui_view, bin_str));

    box.ui_view &= ~FILL_MASK; //把代表填充颜色的位清0  //~1110  0001
    ////00000000000000000010010100000001
printf("bits are %s\n", itobs(box.ui_view, bin_str));

    box.ui_view |= (FILL_BLUE | FILL_GREEN);//重置填充色 1000 | 100 = 1100
    //00000000000000000010010100001101
printf("bits are %s\n", itobs(box.ui_view, bin_str));
    box.ui_view ^= OPAQUE;//转置指示是否透明的位
    //00000000000000000010010100001101
    //00000000000000000000000000000001

    //00000000000000000010010100001100

printf("bits are %s\n", itobs(box.ui_view, bin_str));
    box.ui_view |= BORDER_RED;//错误的方法
    //00000000000000000000001000000000
    //00000000000000000010011100001100
    box.ui_view &= ~STYLE_MASK;//清除样式位
    //00000000000000000011000000000000

    //11111111111111111100111111111111
    //00000000000000000010011100001100
    //00000000000000000000011100001100

printf("bits are %s\n", itobs(box.ui_view, bin_str));

    box.ui_view |= B_DOTTED;//把样式设置为点
    //00000000000000000000011100001100
    //00000000000000000001000000000000

    //00000000000000000001011100001100

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

    printf("\nBox settings using unsigned int view:\n");
    show_settings1(box.ui_view);
    printf("bits are %s\n", itobs(box.ui_view, bin_str));

    return 0;
}

char * itobs(int n, char * ps)
{
    int i;
    static int size = 8 * sizeof(unsigned int);
    for (i = size - 1; i >= 0; i--, n >>= 1) //31 --->0
        ps[i] = (01 & n) + '0';

    ps[size] = '\0';

    return ps;
}

void show_settings1(unsigned short us)
{
    //00000000000000000010010100000111
    //                            111
    printf("Box is %s.\n", us & OPAQUE == OPAQUE ? "opaque" : "transparent");
    printf("The fill color is %s.\n", colors[(us >> 1) & 07]);

    printf("Border %s.\n", us & BORDER == BORDER ? "shown" : "not shown");
    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("unknow type.\n");
        break;
    }

    printf("The border color is %s.\n",colors[(us >> 9) & 07]);
}


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("unknow type.\n");
        break;
    }
}