如何将7.3456788e-12值转换为字符串格式以进行显示? [英] How to convert 7.3456788e-12 value to string format for displaying purpose?

问题描述

大家好，
我只是想将大的浮点值转换为字符串格式.

在我的程序中，

Hi guys,
I just got stuck with conversion of a big floating value to string format.

In my program,

void double_to_string(long double v)
{
  unsigned char res[40];
  
// here i am using compiler library function sprintf() which will give us the string format
  
  sprintf(res,"%f",v);
  if(strlen(res)>14)
  sprintf(res,"%Le",v);// if the result is having more number of digits
  return(res);

}

void fun1()
{
  long double v;
  unsigned char *result_str;
  v = 0.56726*6.456*1e-12; // based on some calculations i used to get this value
  result_str = double_to_string(v);
  print_result(result_str);
}

当我调试代码时，在变量值中，我在double_to_string函数中找到了v的值，例如 3.66223056e-12 .但是在我的sprintf()函数中给出0.000000作为结果.无法将这种类型的值转换为字符串.我如何克服这个问题以获得正确的结果.

注意:我的主要目的是进行如此大的计算，并将其转换为更准确的字符串格式. (就像我们的PC计算器一样)
由于显示区域的限制，如果结果字符串具有更多数字，我将选择指数结果.

我希望我能清楚地提到我的问题.所以，如果有人可以解决这个问题，请帮帮我.对不起我的英语不好.

When i debug my code, in variable values i found the value of v in double_to_string function like this 3.66223056e-12. But in my sprintf() function giving 0.000000 as result. It''s unable to convert such type of value to string. How can i over come this to get the correct results.

Note: My main intention is doing such big calculations and converting them in strings format with more accuracy. (Like our PC calculator)
Due to limitations of my display area, i am choosing exponent results if the resultant string is having more digits.

I hope i mentioned my problem clearly.So, If can any one have solution for this please help me out.Excuse for my poor english.

推荐答案

您对sprintf()向后，输出字符串先行，然后是format语句，然后是要格式化为字符串的值.请参见此处 [

Your arguments to sprintf() are backwards, the output string goes first, then the format statement, then the values to be formatted into the string. See here[^]

Also, the default precision (6) is not usually adequate for very small numbers. anything e-12 is pretty small. Try something like %.20f :)

查看格式类型说明符 [ ^ ]一款适合您的需求.对于您的情况，我建议使用g代码作为最佳选择.

Look at the format type specifiers[^] for the one that suits your needs. In your case I would suggest the g code as the best choice.

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