{
    char a[5];
    Console.WriteLine("请输入一个整数");
    a[1]=Console.ReadLine();
    Console.WriteLine("请输入一个整数");
    a[2]=Console.ReadLine();
    Console.WriteLine("请输入一个整数");
    a[3]=Console.ReadLine();
    if(a[1]>a[2])
       if(a[2]>a[3]) ;
       else { t=a[2];a[2]=a[3];a[3]=t;  }
    else {  t=a[1];a[1]=a[2];a[2]=t;  }  
    if(a[1]>a[3]) ;
       else { t=a[1];a[1]=a[3];a[3]=t;  }
    if(a[2]>a[3]) ;
    else { t=a[2];a[2]=a[3];a[3]=t;  }
    Console.ReadLine("大小顺序为："a[1]+a[2]+a[3]);
}

using System;

class Sort
{
    static void Main()
    {
        int[] value = new int[5];

        for (int i = 0; i < 3; i++)
        {

            Console.WriteLine("Please enter a integer value(3 times):");
            
            value[i] = int.Parse(Console.ReadLine());
            

        }

        for (int i = 1; i < value.Length; i++)  //选择排序算法
        {
              int temp = value[i];
            for (int j = 0; j < value.Length - 1; j++)
            {
                if (temp < value[j])
                {

                    temp = value[j];
                    value[j] = value[i];
                    value[i] = temp;

                }

            }
        }

        for (int i = 0; i < value.Length;i++ )
            Console.WriteLine("The result is:{0}", value[i]);
        Console.ReadKey();   
   
    }

}

数组本身的定义就错了，c#的数组定义和c是不一样的，char[] a; a=new char[5];才对

谢谢了  我是初学者

int[] value = new int[5];
//赋值
........
//

List<int> ints = new List<int>(value);
ints.Sort();

for (int i = 0; i < ints.Count;i++ )
{
    Console.WriteLine("The result is:{0}", ints[i]);
}