转换为ASCII使用C [英] Converting to ASCII in C

问题描述

使用微控制器（PIC18F4580），我需要收集数据并将其发送到供以后分析SD卡。它收集的数据将在0到1023，或0x0和0x3FF对之间的值。

Using a microcontroller (PIC18F4580), I need to collect data and send it to an SD card for later analysis. The data it collects will have values between 0 and 1023, or 0x0 and 0x3FF.

所以我需要做的是转换成1023字面ASCII值的基数为10串（0X31，为0x30，0x32，0x33，...）。

So what I need to do is convert 1023 into a base 10 string of literal ASCII values (0x31, 0x30, 0x32, 0x33, ...).

我的问题是我能想到的分裂位的相隔只有这样需要大量的分工。

My problem is that the only way I can think of to split the digits apart requires a lot of division.

char temp[4];
temp[0] = 1023 % 10;
temp[1] = (1023 % 100) / 10;
temp[2] = (1023 % 1000) / 100;
temp[3] = (1023 % 10000) / 1000;

使用这种方法，发现在n位十进制数的ASCII值需要2n-1个区划。是否有会更快的方法？

Using this method, finding the ASCII values of an n digit decimal number requires 2n-1 divisions. Is there a method that would be faster?

这样做的最终目的是能够快速插入任何笔记本电脑来查看数据的Excel中的图表中的SD卡上的.csv文件拉闸。

The end goal of this is to wind up with a .csv file on the SD card that can quickly be plugged into any laptop to see a graph of the data in Excel.

推荐答案

有一个使用减法做的一种方式，但我不相信这是比使用一个正常的CPU减法和模快（可能处于不同嵌入式环境）。

There's a way of doing it using subtractions, but I am not convinced it's faster than using subtractions and modulus on a "normal" CPU (may be different in an embedded environment).

事情是这样的：

char makedigit (int *number, int base)
{
  static char map[] = "0123456789";
  int ix;

  for (ix=0; *number >= base; ix++) { *number -= base; }

  return map[ix];
}


char *makestring (int number)
{
  static char tmp[5];

  tmp[0] = makedigit(&number, 1000);
  tmp[1] = makedigit(&number, 100);
  tmp[2] = makedigit(&number, 10);
  tmp[3] = makedigit(&number, 1);
  tmp[5] = '\0';

  return tmp;
}

然后，通话makestring（）应导致（静态的，所以覆盖前将它复制）与转换的数字串（零prefixed，在4个字符宽，作为原始假设是在0-1023范围内的值）。

Then, a call to makestring() should result in a (static, so copy it before overwriting) string with the converted number (zero-prefixed, at 4 characters width, as the original assumption is a value in the 0-1023 range).

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