如何将 ascii 字符串转换为二进制？

Question

我正在尝试将 ascii 字符串转换为 C 中的二进制字符串。我找到了这个示例 Converting Ascii to binary in C but I rather not use a recursive function. I tried to write an iterative function as opposed to a recursive function, but the binary string is missing the leading digit. I'm using itoa to convert the string, however itoa is a non standard function so I used the implementation from What is the proper way of implementing a good "itoa()" function?，它是由 Minh Nguyen 提供的。

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

int32_t ascii_to_binary(char *input, char **out, uint64_t len)
{
    uint32_t i;
    uint32_t str_len = len * 8;

    if(len == 0)
    {
        printf("Length argument is zero\n");
        return (-1);
    }

    (*out) = malloc(str_len + 1);
    if((*out) == NULL)
    {
        printf("Can't allocate binary string: %s\n", strerror(errno));
        return (-1);
    }

    if(memset((*out), 0, (str_len)) == NULL)
    {
        printf("Can't initialize memory to zero: %s\n", strerror(errno));
        return (-1);
    }

    for(i = 0; i < len; i++)
        itoa((int32_t)input[i], &(*out)[(i * 8)], 2);

    (*out)[str_len] = '[=10=]';

    return (str_len);
}

int main(void)
{
    int32_t rtrn = 0;
    char *buffer = NULL;

    rtrn = ascii_to_binary("a", &buffer, 1);
    if(rtrn < 0)
    {
        printf("Can't convert string\n");
        return (-1);
    }

    printf("str: %s\n", buffer);

    return (0);
}

我得到 1100001 的 ascii 字符 a，但我应该得到 01100001，那么如何将 ascii 字符串转换为整个二进制字符串？

Answer 1

此程序获取整数（包含 32 位）并将其转换为二进制，对其进行处理以使其适用于 ascii 字符串：

#include <stdio.h>

int main()
{
  int n, c, k;

  printf("Enter an integer in decimal number system\n");
  scanf("%d", &n);

  printf("%d in binary number system is:\n", n);

  for (c = 31; c >= 0; c--)
  {
    k = n >> c;

    if (k & 1)
      printf("1");
    else
      printf("0");
  }

  printf("\n");

  return 0;
}

Answer 2

最好只编写一个简单的函数来使用按位运算符来执行此操作...

#define ON_BIT = 0x01

char *strToBin(char c) {
    static  char    strOutput[10];
    int     bit;

    /*Shifting bits to the right, but don't want the output to be in reverse
     * so indexing bytes with this...
     */
    int     byte;

    /* Add a nul at byte 9 to terminate. */
    strOutput[8] = '[=10=]';

    for (bit = 0, byte = 7; bit < 8; bit++, byte--) {
        /* Shifting the bits in c to the right, each time and'ing it with
         * 0x01 (00000001).
         */
        if ((c >> bit) & BIT_ON)
            /* We know this is a 1. */
            strOutput[byte] = '1';
        else
            strOutput[byte] = '0';
    }

    return strOutput;
}

类似的方法应该可行，您可以通过多种方式实现。希望这有帮助。

Answer 3

您可以将 for 循环更改为如下内容：

for(i = 0; i < len; i++) {
    unsigned char ch = input[i];
    char *o = *out + 8 * i;
    int b;

    for (b = 7; b >= 0; b--)
        *o++ = (ch & (1 << b)) ? '1' : '0';
}

或类似的：

for(i = 0; i < len; i++) {
    unsigned char ch = input[i];
    char *o = &(*out)[8 * i];
    unsigned char b;

    for (b = 0x80; b; b >>= 1)
        *o++ = ch & b ? '1' : '0';
}

如何将 ascii 字符串转换为二进制？

How to convert ascii string to binary?

c

binary

ascii