C# calculate mean of the values in int array

问题

What's the problem when I try to print the average of the values in int array and it prints out something totally different as many times as I have values.

int[] numbers;
numbers = new int[5];
Console.WriteLine("give five integer numbers:");
numbers[0] = Int32.Parse(Console.ReadLine());
numbers[1] = Int32.Parse(Console.ReadLine());
numbers[2] = Int32.Parse(Console.ReadLine());
numbers[3] = Int32.Parse(Console.ReadLine());
numbers[4] = Int32.Parse(Console.ReadLine());
int sum = 0;

foreach (int x in numbers) {
    sum += x;
    int aver = sum / numbers.Length;  
    Console.WriteLine("average: {0}",aver);
}

回答1:

Average should be outside the loop:

foreach (int x in numbers) 
{
   sum += x;
}

int aver = sum / numbers.Length;  
Console.WriteLine("average: {0}",aver);

Or using Linq Extension Methods:

Console.WriteLine("average: {0}", numbers.Average());

回答2:

You could rephrase the loops as

int sum = 0;
foreach (int x in numbers)
{
    sum += x;
}
int aver = sum / numbers.Length;

or simply do the calculation as

int aver = numbers.Average();

by using Linq.

回答3:

Or with linq : var aver = numbers.Average();

https://msdn.microsoft.com/en-us/library/bb399409(v=vs.110).aspx

I ll complete my answer with what is the hood under Average() so ;)

  public static double Average(this IEnumerable<int> source) {
       if (source == null) throw Error.ArgumentNull("source");
       long sum = 0;
       long count = 0;
       checked {
          foreach (int v in source) {
              sum += v;
              count++;
          }
       }
       if (count > 0) return (double)sum / count;
       throw Error.NoElements();
   }

回答4:

Change

foreach (int x in numbers) {
    sum += x;
    int aver = sum / numbers.Length;  Console.WriteLine("average: {0}",aver);
}

foreach (int x in numbers) {
    sum += x;
}
int aver = sum / numbers.Length;  Console.WriteLine("average: {0}",aver);

来源：https://stackoverflow.com/questions/37966950/c-sharp-calculate-mean-of-the-values-in-int-array

标签

arrays

mean