的String.Format - 如何格式化为x位数（不考虑小数位）？ [英] String.Format - How can I format to x digits (regardless of decimal place)?

问题描述

我需要（在我的案件6包括小数点）格式化浮点数为x字符。我的输出还需要包括数字的符号

所以，给出的投入，这里有预期产出

<预类=郎无prettyprint-覆盖> 1.23456 => 1.2345

-12.34567 => -12.345

-0.123456 => -0.1234

1234.567 => 1234.5


请假设总有最后一个字符前的小数位。即不会有 12345.6 号码输入 - 输入将始终小于或等于 9999.9

我想这必须有条件地进行。

解决方案

下面是一个透明的办法做到这一点无需格式字符串（除了F）：

 静态无效的主要（）
 {
双击Y = 1.23456; 
 Console.WriteLine（FormatNumDigits（Y，5））; 
 Y = -12.34567; 
 Console.WriteLine（FormatNumDigits（Y，5））; 
 Y = -0.123456; 
 Console.WriteLine（FormatNumDigits（Y，5））; 
 Y = 1234.567; 
 Console.WriteLine（FormatNumDigits（Y，5））; 
 
 Y = 0.00000234; 
 Console.WriteLine（FormatNumDigits（Y，5））; 
 
 Y = 1.1; 
 Console.WriteLine（FormatNumDigits（Y，5））; 
} 
 
 
公共字符串FormatNumDigits（双号，INT X）{
串asString =（数字> = 0+：？）+ number.ToString（F50，System.Globalization.CultureInfo.InvariantCulture）; 
 
如果（asString.Contains（）'。'）{
如果（asString.Length> X + 2）{
返回asString.Substring（0，X + 2 ）; 
}其他{
 //垫用零
返回asString.Insert（asString.Length，新的String（0，X + 2  -  asString.Length））; 
} 
}其他{
如果（asString.Length> X + 1）{
返回asString.Substring（0，X + 1）; 
}其他{
 //垫用零
返回asString.Insert（1，新的字符串（'0'，X + 1  -  asString.Length））; 
} 
} 
} 
  

输出：

  1.2345 
 -12.345 
 -0.1234 
 1234.5 
 + 0.0000 
 1.1000 
  

修改

注意，它不砍掉尾随零。

I need to format a floating point number to x characters (6 in my case including the decimal point). My output also needs to include the sign of the number

So given the inputs, here are the expected outputs

1.23456   => +1.2345

-12.34567 => -12.345

-0.123456 => -0.1234

1234.567  => +1234.5

Please assume there is always a decimal place before the last character. I.e. there will be no 12345.6 number input - the input will always be less than or equal to 9999.9.

I'm thinking this has to be done conditionally.

解决方案

Here's a transparent way to do it without format strings (except for "F"):

  static void Main()
  {
     double y = 1.23456;
     Console.WriteLine(FormatNumDigits(y,5));
     y= -12.34567;
     Console.WriteLine(FormatNumDigits(y,5));
     y = -0.123456;
     Console.WriteLine(FormatNumDigits(y,5));
     y = 1234.567;
     Console.WriteLine(FormatNumDigits(y,5));

     y = 0.00000234;
     Console.WriteLine(FormatNumDigits(y,5));

     y = 1.1;
     Console.WriteLine(FormatNumDigits(y,5));
  }


  public string FormatNumDigits(double number, int x) {
     string asString = (number >= 0? "+":"") + number.ToString("F50",System.Globalization.CultureInfo.InvariantCulture);

     if (asString.Contains('.')) {
        if (asString.Length > x + 2) {
           return asString.Substring(0, x + 2);
        } else {
           // Pad with zeros
           return asString.Insert(asString.Length, new String('0', x + 2 - asString.Length));
        }
     } else {
        if (asString.Length > x + 1) {
           return asString.Substring(0, x + 1);
        } else {
           // Pad with zeros
           return asString.Insert(1, new String('0', x + 1 - asString.Length));
        }
     }
  }

Output:

  +1.2345
  -12.345
  -0.1234
  +1234.5
  +0.0000
  +1.1000

EDIT

Notice that it does not chop off trailing zeros.

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