1 /*----------------------------------- 2 dualview.c -- 位字段和按位运算符 3 -----------------------------------*/ 4 5 #include <stdio.h> 6 #include <limits.h> 7 8 //边框线样式 9 #define SOLID 0 10 #define DOTTED 1 11 #define DASHED 2 12 13 //三原色 14 #define BLUE 4 15 #define GREEN 2 16 #define RED 1 17 18 //混合颜色 19 #define BLACK (RED & GREEN & BLUE) 20 #define YELLOW (RED | GREEN) 21 #define MAGENTA (RED | BLUE) 22 #define CYAN (GREEN | BLUE) 23 #define WHITE (RED | BLUE | GREEN) 24 25 //按位方法中用到的符号常量 26 #define OPAQUE 0x1 27 #define FILL_BLUE 0x8 28 #define FILL_GREEN 0x4 29 #define FILL_RED 0x2 30 #define FILL_MASK 0xE //掩码 31 #define BORDER 0x100 32 #define BORDER_BLUE 0x800 33 #define BORDER_GREEN 0x400 34 #define BORDER_RED 0x200 35 #define BORDER_MASK 0xE00 36 #define B_SOLID 0 37 #define B_DOTTED 0x1000 38 #define B_DASHED 0x2000 39 #define STYLE_MASK 0x3000 40 41 struct box_props 42 { 43 unsigned int opaque : 1; 44 unsigned int fill_color : 3; 45 unsigned int : 4; 46 unsigned int show_border : 1; 47 unsigned int border_color : 3; 48 unsigned int border_style : 2; 49 unsigned int : 2; 50 }; 51 52 //把数据看作结构或 unsigned short 类型的变量 53 union Views 54 { 55 struct box_props st_view; 56 unsigned short us_view; 57 }; 58 59 const char *color[8] = 60 { 61 "black", "red", "green", "yellow", "blue", "magenta", "cyan", "white" 62 }; 63 64 void show_settings(const struct box_props *pb); 65 void show_setting1(unsigned short); 66 char* itobs(int n, char *ps); 67 void show_bstr(const char *str); 68 69 int main() 70 { 71 printf("size of struct box_props is %d bit\n", CHAR_BIT * sizeof(struct box_props)); 72 printf("size of unsigned short is %d bit\n", CHAR_BIT * sizeof(unsigned short)); 73 74 //创建 Vies 联合，并初始化 initialize struct box view 75 union Views box = {{true, YELLOW, true, GREEN, DASHED}}; 76 char bin_str[8 * sizeof(unsigned int) + 1]; 77 78 printf("\nOriginal box settings:\n"); 79 show_settings(&box.st_view); 80 printf("\nBox settings using unsigned int view:\n"); 81 show_setting1(box.us_view); 82 //printf("bits are %s\n", itobs(box.us_view, bin_str)); 83 printf("bits are:\n"); 84 show_bstr(itobs(box.us_view, bin_str)); 85 86 box.us_view &= ~FILL_MASK; //把表示填充色的位清零 87 box.us_view |= CYAN; //重置填充色 88 box.us_view ^= OPAQUE; //切换透明位 89 box.us_view &= ~BORDER_MASK; //边框颜色位清零 90 box.us_view |= BORDER_RED; 91 box.us_view &= ~STYLE_MASK; //样式位清零 92 box.us_view |= B_DOTTED; //边框样式设置为点 93 printf("\nModified box settings:\n"); 94 show_settings(&box.st_view); 95 printf("\nBox settings using unsigned int view:\n"); 96 show_setting1(box.us_view); 97 //printf("bits are %s\n", itobs(box.us_view, bin_str)); 98 printf("bits are:\n"); 99 show_bstr(itobs(box.us_view, bin_str)); 100 101 return 0; 102 } 103 104 void show_settings(const struct box_props *pb) 105 { 106 printf("Box is %s.\n", pb->opaque ? "opaque" : "transparent"); 107 printf("The fill color is %s.\n", color[pb->fill_color]); 108 printf("Border %s.\n", pb->show_border ? "shown" : "not shown"); 109 printf("The border color is %s.\n", color[pb->