c - C中Ascii Char转二进制的解释

Question

谁能详细解释一下以下 Char to Binary 函数在 C 中的工作原理？

具体来说，移位和逻辑如何在迭代中工作

#include <stdio.h>
#include <limits.h>
void printCharAsBinary(char c) {
    int i;
    for(i = CHAR_BIT; i >= 0; i--){
        printf("%d", ( unsigned int )( ( c & (1 << i) ) ? 1 : 0) );
    }
}

void printCharAsBinaryVer2(char c){
    int bit_index;
    for (bit_index = CHAR_BIT; bit_index >= 0; --bit_index)
    {
        int bit = ( unsigned int ) (c >> bit_index) & 1;
        printf("%d", bit);
    }
}

如果有帮助，您可以在此处查看它们的运行情况: http://code.geeksforgeeks.org/zC22WO

---

根据答案更新:

F 是十进制的 70

70 在二进制中是01000110

使用以下代码:

#include <stdio.h>
#include <limits.h>
void printCharAsBinary(char c) {
    int i;
    for(i = CHAR_BIT; i >= 0; i--){
        printf("%d", ( unsigned int )( ( c & (1 << i) ) ? 1 : 0) );
    }
}

迭代将是:

01000110 & 10000000 = 00000000  RESULT is 0   so PRINT 0
01000110 & 01000000 = 01000000  RESULT is > 0 so PRINT 1
01000110 & 00100000 = 00000000  RESULT is 0   so PRINT 0
01000110 & 00010000 = 00000000  RESULT is 0   so PRINT 0
01000110 & 00001000 = 00000000  RESULT is 0   so PRINT 0
01000110 & 00000100 = 00000100  RESULT is > 0 so PRINT 1
01000110 & 00000010 = 00000000  RESULT is > 0 so PRINT 1
01000110 & 00000001 = 00000000  RESULT is 0   so PRINT 0

使用以下代码:

void printCharAsBinaryVer2(char c){
    int bit_index;
    for (bit_index = CHAR_BIT; bit_index >= 0; --bit_index)
    {
        int bit = ( unsigned int ) (c >> bit_index) & 1;
        printf("%d", bit);
    }
}

00000000 & 00000001 = 00000000  RESULT is 0   so PRINT 0
00000001 & 00000001 = 00000001  RESULT is > 0 so PRINT 1
00000010 & 00000001 = 00000000  RESULT is 0   so PRINT 0
00000100 & 00000001 = 00000000  RESULT is 0   so PRINT 0
00001000 & 00000001 = 00000000  RESULT is 0   so PRINT 0
00010001 & 00000001 = 00000001  RESULT is > 0 so PRINT 1
00100011 & 00000001 = 00000001  RESULT is > 0 so PRINT 1
01000110 & 00000001 = 00000000  RESULT is 0   so PRINT 0

Answer 1

Char 在二进制表示中有 8 位。 您在这样的字符表示中将每个位打印为 1 或 0:

您通过 for 循环并使用计数器向左进行逻辑移位，然后使用按位 AND 检查位是否已设置。如果是，则打印 1，否则打印 0。

假设您的二进制数是 01010101

For 循环迭代是:

1. 01010101 & 10000000 = 00000000 结果是0，你打印0
2. 01010101 & 01000000 = 01000000 结果是 > 0，你打印 1
3. 01010101 & 00100000 = 00000000 结果是0，你打印0
4. 等等。

打印完所有内容后，您将得到 01010101。