Question

我在树屋做了这个挑战，我无法弄清楚为什么我会得到＆＃34; Nan＆＃34;当我输入＆＃34;完成＆＃34;。我想这是因为它试图划分，但我不明白为什么它会保持在0。无论如何，到目前为止我的代码是：

using System;

namespace averager
{
    class Program
    {
        static void Main()
        {
            var numberTotal = 0.0;
            var entryNumber = 0.0;
            var average = (numberTotal/entryNumber);

          while(true)
          {
            // Prompt user to enter a number or enter "done" to see the average
            Console.Write("Enter a number or type \"done\" to see the average: ");
            var entry = Console.ReadLine();


            if(entry.ToLower() == "done")
            {
              Console.WriteLine("The average is: " + average);
              break;
            }
            try
            {


              var number = double.Parse(entry);
              numberTotal += + number;
              entryNumber += + 1.0;

            }
            catch(FormatException)
            {
              Console.WriteLine("That is not a valid input");
              continue;
            }

          }

        }
    }
}

Answer 1

Console.WriteLine("The average is: " + average);

您在程序开始时设置平均值，但在用户输入值后从未实际设置它。如果更改上面的行以实际运行计算：

Console.WriteLine("The average is: " + numberTotal/entryNumber);

您将看到预期的结果

Answer 2

看！您刚刚分配了avegare 一次：

 // 0.0 / 0.0 == NAN
 var average = (numberTotal/entryNumber);

并且从那时起就不要改变它：

 var number = double.Parse(entry);
 //what do you mean by unary + here?
 numberTotal += + number;
 //what do you mean by unary + here? 
 entryNumber += + 1.0;

 // average is NOT updated

最后，您输出的初始average是NAN：

  Console.WriteLine("The average is: " + average);

添加average计算

 var number = double.Parse(entry);
 numberTotal += number;  
 entryNumber += 1.0;

 //TODO: do not forget to change average
 average = numberTotal / entryNumber;

Answer 3

在变量变化之前计算平均值，并且仍然为零。永远不会再计算平均值。读入新值后，您应该再次计算平均值。

返回平均，非常简单的C＃代码

3 个答案: