C＃到Lambda - 計算小數位數/第一個有效小數

Question

出於好奇，下面會有一個等效的Lambda表達式嗎？

...剛剛開始使用lambda，不熟悉zip等方法...

//Pass in a double and return the number of decimal places
//ie. 0.00009 should result in 5

//EDIT: Number of decimal places is good.
//However, what I really want is the position of the first non-zero digit 
//after the decimal place.

int count=0;
while ((int)double_in % 10 ==0)
{
double_in*=10;
count++;
}

Answer 1

 double1.ToString().SkipWhile(c => c!='.').Skip(1).Count()

例如：

double double1 = 1.06696;
int count = double1.ToString().SkipWhile(c => c!='.').Skip(1).Count(); // count = 5;

double double2 = 16696;
int count2 = double2.ToString().SkipWhile(c => c!='.').Skip(1).Count(); // count = 0;

Answer 2

Math.Ceiling(-Math.Log(double_in, 10))

Answer 3

我會編寫一個InfiniteSequence函數

/// <summary>
/// Returns an inifinte sequence of integers starting with 1
/// </summary>
public static IEnumerable<int> InfiniteSequence() {
  int value = 0;
  while (true) {
    yield return ++value;
  }
}

（無論如何在.NET中都缺少這種無限枚舉:) :)然后使用它就像

var count = InfiniteSequence().Select(i => (int)(double_in * Math.Power(10,i))).TakeWhile(v=>v%10==0).Count();

這將是原始代碼的直接翻譯（除了計算10的冪的方式之外）。

Answer 4

如果認為這更有可能回答你的問題，並且文化不變。

Math.Max(0, num.ToString().Length - Math.Truncate(num).ToString().Length - 1)