Bit Operation
位操作
位运算符
按位与，或，非，异或
#include <stdio.h>
void printBits(int num)
{
// 获取整数的位数
int bits = sizeof(num) * 8; // sizeof(num) 返回整数的大小（以字节为单位），乘以 8 得到位数
// 遍历整数的每一位
for (int i = bits - 1; i >= 0; i--)
{
// 检查当前位是否为 1
if (num & (1 << i))
{
printf("1"); // 如果当前位是 1，则打印 1
}
else
{
printf("0"); // 如果当前位是 0，则打印 0
}
}
printf("\n"); // 打印换行符，以便在不同的位之间分隔
}
int main()
{
int a = 0b011;
printBits(a); // 00000000000000000000000000000011
// 按位取反：～
printBits(~a); // 11111111111111111111111111111100
// 按位与: &
printBits(0b10001 & 0b10010); // 00000000000000000000000000010000
// 按位或: |
printBits(0b10001 | 0b10010); // 00000000000000000000000000010011
// 按位异或: ^
printBits(0b10001 ^ 0b10010); // 00000000000000000000000000000011
}
移位：左右
#include <stdio.h>
void printBits(int num)
{
// 获取整数的位数
int bits = sizeof(num) * 8; // sizeof(num) 返回整数的大小（以字节为单位），乘以 8 得到位数
// 遍历整数的每一位
for (int i = bits - 1; i >= 0; i--)
{
// 检查当前位是否为 1
if (num & (1 << i))
{
printf("1"); // 如果当前位是 1，则打印 1
}
else
{
printf("0"); // 如果当前位是 0，则打印 0
}
}
printf("\n"); // 打印换行符，以便在不同的位之间分隔
}
int main()
{
int positive = 3;
int negtiave = -3;
printBits(positive);
printBits(positive << 1);
printBits(positive << 2);
printBits(positive << 3);
printBits(positive >> 1);
printBits(positive >> 2);
printBits(positive >> 3);
// 00000000000000000000000000000011
// 00000000000000000000000000000110
// 00000000000000000000000000001100
// 00000000000000000000000000011000
// 00000000000000000000000000000001
// 00000000000000000000000000000000
// 00000000000000000000000000000000
printBits(negtiave);
printBits(negtiave << 1);
printBits(negtiave << 2);
printBits(negtiave << 3);
printBits(negtiave >> 1);
printBits(negtiave >> 2);
printBits(negtiave >> 3);
// 11111111111111111111111111111101
// 11111111111111111111111111111010
// 11111111111111111111111111110100
// 11111111111111111111111111101000
// 11111111111111111111111111111110
// 11111111111111111111111111111111
// 11111111111111111111111111111111
}位字段
Demo
/* dualview.c -- bit fields and bitwise operators */
#include <stdio.h>
#include <stdbool.h>
#include <limits.h>
/* BIT-FIELD CONSTANTS */
/* 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)
/* BITWISE CONSTANTS */
#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
{
bool opaque : 1;
unsigned int fill_color : 3;
unsigned int : 4;
bool show_border : 1;
unsigned int border_color : 3;
unsigned int border_style : 2;
unsigned int : 2;
};
union Views /* look at data as struct or as unsigned short */
{
struct box_props st_view;
unsigned short us_view;
};
void show_settings(const struct box_props *pb);
void show_settings1(unsigned short);
char *itobs(int n, char *ps);
int main(void)
{
/* create Views object, initialize struct box view */
union Views box = {{true, YELLOW, true, 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.us_view);
printf("bits are %s\n",
itobs(box.us_view, bin_str));
box.us_view &= ~FILL_MASK; /* clear fill bits */
box.us_view |= (FILL_BLUE | FILL_GREEN); /* reset fill */
box.us_view ^= OPAQUE; /* toggle opacity */
box.us_view |= BORDER_RED; /* wrong approach */
box.us_view &= ~STYLE_MASK; /* clear style bits */
box.us_view |= B_DOTTED; /* set style to dotted */
printf("\nModified box settings:\n");
show_settings(&box.st_view);
printf("\nBox settings using unsigned int view:\n");
show_settings1(box.us_view);
printf("bits are %s\n",
itobs(box.us_view, bin_str));
return 0;
}
void show_settings(const struct box_props *pb)
{
printf("Box is %s.\n",
pb->opaque == true ? "opaque" : "transparent");
printf("The fill color is %s.\n", colors[pb->fill_color]);
printf("Border %s.\n",
pb->show_border == true ? "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");
}
}
void show_settings1(unsigned short us)
{
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("unknown type.\n");
}
printf("The border color is %s.\n",
colors[(us >> 9) & 07]);
}
char *itobs(int n, char *ps)
{
int i;
const static int size = CHAR_BIT * sizeof(int);
for (i = size - 1; i >= 0; i--, n >>= 1)
ps[i] = (01 & n) + '0';
ps[size] = '\0';
return ps;
}
// (base) kimshan@MacBook-Pro output % ./"dualview"
// Original box settings:
// Box is opaque.
// The fill color is yellow.
// Border shown.
// The border color is green.
// The border style is dashed.
// Box settings using unsigned int view:
// box is opaque.
// The fill color is yellow.
// Border shown.
// The border style is dashed.
// The border color is green.
// bits are 00000000000000000010010100000111
// Modified box settings:
// Box is transparent.
// The fill color is cyan.
// Border shown.
// The border color is yellow.
// The border style is dotted.
// Box settings using unsigned int view:
// box is transparent.
// The fill color is cyan.
// Border shown.
// The border style is dotted.
// The border color is yellow.
// bits are 00000000000000000001011100001100最后更新于
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