要求输入三个数，判断其大小，并按从小到大的顺序排列输出！

排序几乎所有基础书上都有，随便找本看，或者百度搜C# 排序

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Single[] single = new Single[3];
            for (int i = 0; i < 3; i++)
            {
                Console.WriteLine("Please input a number:");
                try
                {

                    single[i] = Convert.ToSingle(Console.ReadLine());
                    
                }
                catch (Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }
               
            }

            Single temp = single[0],tt=0;
            for (int i = 1; i <3; i++)//判断大小并置换位置
            {
                if (single[i-1] > single[i])
                {
                    tt = single[i-1];
                    single[i-1] = single[i];
                    single[i] = tt;
                }
            }
            string temps ="";
            for (int i = 0; i < 3; i++)
            {
                temps = temps+single[i] + " ";
            }
            Console.WriteLine("The order is:" + temps);
            Console.ReadLine();

        }
    }
}

可以放到arraylist 里可以利用sort()方法排序

4楼的方法更简单