C# 计算布尔数组中真（或假）元素的数量？
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calculate number of true (or false) elements in a bool array?
提问by Evgeny
Suppose I have an array filled with Boolean values and I want to know how many of the elements are true.
假设我有一个填充了布尔值的数组，我想知道有多少元素是真的。
private bool[] testArray = new bool[10] { true, false, true, true, false, true, true, true, false, false };
int CalculateValues(bool val)
{
return ???
}
CalculateValues should return 6 if val is true, or 4 if val is false.
如果 val 为真，CalculateValues 应返回 6，如果 val 为假，则应返回 4。
Obvious solution:
明显的解决方案：
int CalculateValues(bool val)
{
int count = 0;
for(int i = 0; i<testArray.Length;i++)
{
if(testArray[i] == val)
count++;
}
return count;
}
Is there an "elegant" solution?
有没有“优雅”的解决方案？
采纳答案by Chris Knight
Use LINQ. You can do testArray.Where(c => c).Count();for true count or use testArray.Where(c => !c).Count();for false check
使用 LINQ。您可以testArray.Where(c => c).Count();进行真实计数或testArray.Where(c => !c).Count();用于错误检查
回答by SLaks
return testArray.Count(c => c)
回答by Reed Copsey
You can use:
您可以使用：
int CalculateValues(bool val)
{
return testArray.Count(c => c == val);
}
This handles the trueand falsechecks, based on your valparameter.
这将根据您的参数处理true和false检查val。
回答by DeanG
Try something like this :
尝试这样的事情：
bool[] testArray = new bool[10] { true, false, true, true, false, true, true, true, false, false };
bool inVal = true;
int i;
i = testArray.Count(ai => ai == inVal);
回答by Nicholas Carey
I like this:
我喜欢这个：
int trueCount = boolArray.Sum( x => x ? 1 : 0 ) ;
回答by Matthew Strawbridge
While testArray.Count(c => c)is functionally correct, it's not intuitive and there's a risk that some later developer will strip out the c => cpart thinking it doesn't do anything.
虽然testArray.Count(c => c)在功能上是正确的，但它并不直观，并且存在一些后来的开发人员会c => c认为它不做任何事情而剥离该部分的风险。
This can be derisked by declaring the lambda function separately with a meaningful name:
这可以通过使用有意义的名称单独声明 lambda 函数来消除：
Func<bool, bool> ifTrue = x => x;
return testArray.Count(ifTrue);
