典雅确定是否多于一个的布尔值为＆QUOT;真＆QUOT; [英] Elegantly determine if more than one boolean is "true"

问题描述

我有一组五个布尔值。如果其中一个以上的是真实的我想excecute一个特定的功能。什么是你能想到的，最优雅的方式，可以让我在一个if（）语句检查此条件？目标语言是C＃，但我很感兴趣，在其他语言的解决方案（只要我们不是在谈论具体的内置函数）。

I have a set of five boolean values. If more than one of these are true I want to excecute a particular function. What is the most elegant way you can think of that would allow me to check this condition in a single if() statement? Target language is C# but I'm interested in solutions in other languages as well (as long as we're not talking about specific built-in functions).

一个有趣的选择是将布尔值存储在一个字节中，执行右移，并与原来的字节比较。类似如果（myByte＆安培;及（myByte＆GT;＆GT; 1））（？通过bitArray）但这需要转换不同的布尔一个字节和似乎有点（双关语意）笨拙... 对不起，本来应该是的如果（myByte及（myByte - 1））的 [/编辑] 的

One interesting option is to store the booleans in a byte, do a right shift and compare with the original byte. Something like if(myByte && (myByte >> 1)) But this would require converting the separate booleans to a byte (via a bitArray?) and that seems a bit (pun intended) clumsy... [edit]Sorry, that should have been if(myByte & (myByte - 1)) [/edit]

请注意：这当然是非常接近传统的口算，侧身加法还是汉明权重编程问题 - 但不完全一样。我并不需要知道有多少位被置位，仅当它是多台。我希望有一个更简单的实现这种方式。

Note: This is of course very close to the classical "population count", "sideways addition" or "Hamming weight" programming problem - but not quite the same. I don't need to know how many of the bits are set, only if it is more than one. My hope is that there is a much simpler way to accomplish this.

推荐答案

如何

  if ((bool1? 1:0) + (bool2? 1:0) + (bool3? 1:0) + 
      (bool4? 1:0) + (bool5? 1:0) > 1)
      // do something

或通用的方法是...

or a generalized method would be...

   public bool ExceedsThreshold(int threshold, IEnumerable<bool> bools)
    {
       int trueCnt = 0;
       foreach(bool b in bools)
          if (b && (++trueCnt > threshold)) 
              return true;
       return false;          
    } 

或使用LINQ由其他答案的建议：

or using LINQ as suggested by other answers:

    public bool ExceedsThreshold(int threshold, IEnumerable<bool> bools)
    { return bools.Count(b => b) > threshold; }

编辑（添加乔尔Coehoorn建议：
（在.net 2.x和更高版本）

EDIT (to add Joel Coehoorn suggestion: (in .Net 2.x and later)

    public void ExceedsThreshold<T>(int threshold, 
                      Action<T> action, T parameter, 
                      IEnumerable<bool> bools)
    { if (ExceedsThreshold(threshold, bools)) action(parameter); }

或在.net 3.5及更高版本：

or in .Net 3.5 and later:

    public void ExceedsThreshold(int threshold, 
            Action action, IEnumerable<bool> bools)
    { if (ExceedsThreshold(threshold, bools)) action(); }

或作为扩展的IEnumerable＆LT;布尔＆GT;

  public static class IEnumerableExtensions
  {
      public static bool ExceedsThreshold<T> 
         (this IEnumerable<bool> bools, int threshold)
      { return bools.Count(b => b) > threshold; }
  }

使用然后将：

  var bools = new [] {true, true, false, false, false, false, true};
  if (bools.ExceedsThreshold(3))
      // code to execute  ...

这篇关于典雅确定是否多于一个的布尔值为＆QUOT;真＆QUOT;的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！