C_BitManipulation.html-优快云博客

https://www.sharetechnote.com/html/C_BitManipulation.html

我更喜欢C语言，在大多数情况下。然而，我对C语言不满意的是它没有太多的内置位操作功能。在大多数应用程序中，你可能不需要这种位操作，但如果你正在从事嵌入式系统编程或解析程序，你需要进行大量的位操作。在这个页面上，我将发布各种情况下操纵位和字节的技巧。这不是很难，但如果你不熟悉这些技巧，看起来会很混乱。我将继续添加这些位操作的示例，以便于你将其作为小型字典使用。

例句：

1. 以二进制格式打印数字

2. 移位二进制数

3. 取出特定位

4. 设置特定位（设为'1'）并取消设置所有其他位（设为'0'）

5. 取消设置特定位（设为'0'）并设置所有其他位（设为'1'）

6. 设置特定位（设为'1'），而不影响其他位

7. 取消设置特定位（设为'0'），而不影响其他位

8. 设置多个位（设为'1'）并取消设置所有其他位（设为'0'）

Example 1 > Printing Numbers in Binary Format

void printInt2Bin(int a)

{

int i,n;

n = sizeof(int)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

void printChar2Bin(int a)

{

int i,n;

n = sizeof(char)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

int main()

{

printInt2Bin(123);

printf("\n");

printChar2Bin(123);

return 1;

}

Result :----------------------------------

printInt2Bin(123); ==> 00000000 00000000 00000000 01111011

printChar2Bin(123); ==> 01111011

Example 2 > Shifting the binary number

#include <stdio.h>

void printInt2Bin(int a)

{

int i,n;

n = sizeof(int)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

void printChar2Bin(int a)

{

int i,n;

n = sizeof(char)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

int main()

{

char a = 100;

printf("a (Dec) => %d\n",a);

printf("a (Bin) => ");

printChar2Bin(a);

printf("\n");

printf("(a >> 1) => ");

printChar2Bin(a >> 1); // Shift the number 'a' to the right by 1 bit

printf("\n");

printf("(a >> 4) => ");

printChar2Bin(a >> 4); // Shift the number 'a' to the right by 4 bits

printf("\n");

printf("(a >> 8) => ");

printChar2Bin(a >> 8); // Shift the number 'a' to the right by 8 bits

printf("\n");

printf("(a >> 10)=> ");

printChar2Bin(a >> 10); // Shift the number 'a' to the right by 10 bits

printf("\n");

printf("(a << 1) => ");

printChar2Bin(a << 1); // Shift the number 'a' to the left by 4 bit

printf("\n");

printf("(a << 4) => ");

printChar2Bin(a << 4); // Shift the number 'a' to the left by 4 bits

printf("\n");

printf("(a << 8) => ");

printChar2Bin(a << 8); // Shift the number 'a' to the left by 8 bits

printf("\n");

printf("(a << 10)=> ");

printChar2Bin(a << 10); // Shift the number 'a' to the left by 10 bits

return 1;

}

Result :----------------------------------

a (Dec) => 100

a (Bin) => 01100100

(a >> 1) => 00110010

(a >> 4) => 00000110

(a >> 8) => 00000000

(a >> 10)=> 00000000

(a << 1) => 11001000

(a << 4) => 01000000

(a << 8) => 00000000

(a << 10)=> 00000000

Example 3 > Take out a specific bit

#include <stdio.h>

void printInt2Bin(int a)

{

int i,n;

n = sizeof(int)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

void printChar2Bin(int a)

{

int i,n;

n = sizeof(char)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

int main()

{

char a = 100;

printf("a (Dec) => %d\n",a);

printf("a (Bin) => ");

printChar2Bin(a);

printf("\n");

printf("(a >> 0) & 1 => %d", (a >> 0) & 1 );

printf("\n");

printf("(a >> 1) & 1 => %d", (a >> 1) & 1 );

printf("\n");

printf("(a >> 2) & 1 => %d", (a >> 2) & 1 );

printf("\n");

printf("(a >> 3) & 1 => %d", (a >> 3) & 1 );

printf("\n");

printf("(a >> 4) & 1 => %d", (a >> 4) & 1 );

printf("\n");

printf("(a >> 5) & 1 => %d", (a >> 5) & 1 );

printf("\n");

printf("(a >> 6) & 1 => %d", (a >> 6) & 1 );

printf("\n");

printf("(a >> 7) & 1 => %d", (a >> 7) & 1 );

return 1;

}

Result :----------------------------------

a (Dec) => 100

a (Bin) => 01100100

(a >> 0) & 1 => 0

(a >> 1) & 1 => 0

(a >> 2) & 1 => 1

(a >> 3) & 1 => 0

(a >> 4) & 1 => 0

(a >> 5) & 1 => 1

(a >> 6) & 1 => 1

(a >> 7) & 1 => 0

Example 4 > Setting a specific bit (set it to be '1') and Unsetting all other bits (set it to be '0')

#include <stdio.h>

void printInt2Bin(int a)

{

int i,n;

n = sizeof(int)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

void printChar2Bin(int a)

{

int i,n;

n = sizeof(char)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

int main()

{

char a = 100;

printf("a (Dec) => %d\n",a);

printf("a (Bin) => ");

printChar2Bin(a);

printf("\n");

printf("a = (1 << 0) => ");

a = (1 << 0);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 1) => ");

a = (1 << 1);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 2) => ");

a = (1 << 2);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 3) => ");

a = (1 << 3);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 4) => ");

a = (1 << 4);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 5) => ");

a = (1 << 5);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 6) => ");

a = (1 << 6);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 7) => ");

a = (1 << 7);

printChar2Bin(a);

return 1;

}

Result :------------------------------

a (Dec) => 100

a (Bin) => 01100100 // this existing value does not affect any of the following operation

a = (1 << 0) => 00000001

a = (1 << 1) => 00000010

a = (1 << 2) => 00000100

a = (1 << 3) => 00001000

a = (1 << 4) => 00010000

a = (1 << 5) => 00100000

a = (1 << 6) => 01000000

a = (1 << 7) => 10000000

Example 5 > Unsetting a specific bit (set it to be '0') and Setting all other bits (set it to be '1')

#include <stdio.h>

void printInt2Bin(int a)

{

int i,n;

n = sizeof(int)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

void printChar2Bin(int a)

{

int i,n;

n = sizeof(char)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

int main()

{

char a = 100;

printf("a (Dec) => %d\n",a);

printf("a (Bin) => ");

printChar2Bin(a);

printf("\n");

printf("a = (1 << 0) => ");

a = ~(1 << 0);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 1) => ");

a = ~(1 << 1);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 2) => ");

a = ~(1 << 2);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 3) => ");

a = ~(1 << 3);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 4) => ");

a = ~(1 << 4);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 5) => ");

a = ~(1 << 5);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 6) => ");

a = ~(1 << 6);

printChar2Bin(a);

printf("\n");

printf("a = (1 << 7) => ");

a = ~(1 << 7);

printChar2Bin(a);

return 1;

}

Result :----------------------------

a (Dec) => 100

a (Bin) => 01100100 // this existing value does not affect any of the following operation

a = (1 << 0) => 11111110

a = (1 << 1) => 11111101

a = (1 << 2) => 11111011

a = (1 << 3) => 11110111

a = (1 << 4) => 11101111

a = (1 << 5) => 11011111

a = (1 << 6) => 10111111

a = (1 << 7) => 01111111

Example 5 > Setting a specific bit (set it to be '1') without affecting other bits

#include <stdio.h>

void printInt2Bin(int a)

{

int i,n;

n = sizeof(int)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

void printChar2Bin(int a)

{

int i,n;

n = sizeof(char)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

int main()

{

char a = 100;

printf("a (Dec) => %d\n",a);

printf("a (Bin) => ");

printChar2Bin(a);

printf("\n");

printf("a | (1 << 0) => ");

printChar2Bin(a | (1 << 0));

printf("\n");

printf("a | (1 << 1) => ");

printChar2Bin(a | (1 << 1));

printf("\n");

printf("a | (1 << 2) => ");

printChar2Bin(a | (1 << 2));

printf("\n");

printf("a | (1 << 3) => ");

printChar2Bin(a | (1 << 3));

printf("\n");

printf("a | (1 << 4) => ");

printChar2Bin(a | (1 << 4));

printf("\n");

printf("a | (1 << 5) => ");

printChar2Bin(a | (1 << 5));

printf("\n");

printf("a | (1 << 6) => ");

printChar2Bin(a | (1 << 6));

printf("\n");

printf("a | (1 << 7) => ");

printChar2Bin(a | (1 << 7));

return 1;

}

Result :----------------------------------

a (Dec) => 100

a (Bin) => 01100100

a | (1 << 0) => 01100101

a | (1 << 1) => 01100110

a | (1 << 2) => 01100100

a | (1 << 3) => 01101100

a | (1 << 4) => 01110100

a | (1 << 5) => 01100100

a | (1 << 6) => 01100100

a | (1 << 7) => 11100100

Example 6 > Unsetting a specific bit (set it to be '0') without affecting other bits

#include <stdio.h>

void printInt2Bin(int a)

{

int i,n;

n = sizeof(int)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

void printChar2Bin(int a)

{

int i,n;

n = sizeof(char)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

int main()

{

char a = 100;

printf("a (Dec) => %d\n",a);

printf("a (Bin) => ");

printChar2Bin(a);

printf("\n");

printf("a & ~(1 << 0) => ");

printChar2Bin(a & ~(1 << 0));

printf("\n");

printf("a & ~(1 << 1) => ");

printChar2Bin(a & ~(1 << 1));

printf("\n");

printf("a & ~(1 << 2) => ");

printChar2Bin(a & ~(1 << 2));

printf("\n");

printf("a & ~(1 << 3) => ");

printChar2Bin(a & ~(1 << 3));

printf("\n");

printf("a & ~(1 << 4) => ");

printChar2Bin(a & ~(1 << 4));

printf("\n");

printf("a & ~(1 << 5) => ");

printChar2Bin(a & ~(1 << 5));

printf("\n");

printf("a & ~(1 << 6) => ");

printChar2Bin(a & ~(1 << 6));

printf("\n");

printf("a & ~(1 << 7) => ");

printChar2Bin(a & ~(1 << 7));

return 1;

}

Result :----------------------------------

a (Dec) => 100

a (Bin) => 01100100

a & ~(1 << 0) => 01100100

a & ~(1 << 1) => 01100100

a & ~(1 << 2) => 01100000

a & ~(1 << 3) => 01100100

a & ~(1 << 4) => 01100100

a & ~(1 << 5) => 01000100

a & ~(1 << 6) => 00100100

a & ~(1 << 7) => 01100100

Example 7 > Setting multiple bit (set it to be '1') and Unsetting all other bits (set it to be '0')

#include <stdio.h>

void printInt2Bin(int a)

{

int i,n;

n = sizeof(int)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

void printChar2Bin(int a)

{

int i,n;

n = sizeof(char)*8;

for(i=n-1;i>=0;i--) {

printf("%d",(a >> i) & 1);

if(i % 8 == 0) printf(" ");

}

int main()

{

char a = 100;

printf("a (Dec) => %d\n",a);

printf("a (Bin) => ");

printChar2Bin(a);

printf("\n");

a = (1 << 5) | (1 << 3) | (1 << 0);

printf("(1 << 5) | (1 << 3) | (1 << 0) => ");

printChar2Bin(a);

return 1;

}

Result :-----------------

a (Dec) => 100

a (Bin) => 01100100

(1 << 5) | (1 << 3) | (1 << 0) => 00101001 // Set the bits 0,3,5 to be '1'

// and set all other bits to be '0'

// regardless of the existing value