using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1dishierzhou2
{
    class Program
    {
        static double Min(double[] num)
        {
            double min = num[0];
            for (int i = 0; i < 10; i++)
            {
                if (min > num[i])
                {
                    min = num[i];
                }
            }
            return min;

        }
        static double Max(double[] num)
        {
            double max = num[0];
            for (int i = 0; i < 10; i++)
            {
                if (max < num[i])
                {
                    max = num[i];
                }
            }
            return max;
 
        }
        static double Average(double[] num)
        {
            double average = 0, sum = 0;
            for (int i = 0; i < 10; i++)
            {
                sum = sum + num[i];
            }
            average = sum / 10;

            return average;

        }
        
        static void Main(string[] args)
        {
            Console.WriteLine("输入10个数存入数组，并求其最大值、最小值和平均值");  
            double[] num = new double[10];  
            for (int i = 0; i < 10; i++)  
           {  
             Console.Write("请您输入第{0}个数：", i + 1);  
             num[i] = double.Parse(Console.ReadLine());  
           }  
           double  min1 = Min(num);
            Console.WriteLine("您输入10个数中最小值为：{0}",min1);  
            double max1 = Max(num);  
            Console.WriteLine("您输入10个数中最大值为：{0}",max1);  
            double average1 = Average(num);  
            Console.WriteLine("您输入10个数中平均值为：{0}",average1);  
           
          Console.ReadKey();  
      }  


        }
        
        
}

输出结果：

实验总结：

必须把方法体放在main函数前面！