闲来无事做，把最近碰到的一些小面试题整理一下，单例模式，冒泡排序，递归

    /// <summary>
    /// 单例模式
    /// </summary>
    /// <typeparam name="T"></typeparam>
   public class Singleton<T> where T:new () 
    {
       public static T Instance { get { return SingletonCreator.instance; } }
       public class SingletonCreator 
       {
        internal readonly static T instance=new T(); 
       }
    }

/// <summary>
        ///  冒泡排序
        /// </summary>
        public static void MaoPao()
        {
            int[] arry = { 30, 6, 5, 15, 13, 18, 10, 36, 25 };
            for (int i = 0; i < arry.Length - 1; i++)
            {
                for (int j = i + 1; j < arry.Length; j++)
                {
                    int temp;
                    if (arry[i] > arry[j])
                    {
                        temp = arry[i];
                        arry[i] = arry[j];
                        arry[j] = temp;
                    }
                }
            }

            foreach (var item in arry)
            {
                Console.Write("-" + item + "-");
            }
        }
    }

 /// <summary>
        /// 递归算法
        /// </summary>
        public static int Recursion(int m)
        {
            if (m <= 1)
                return 1;
            else
            {
                return m * Recursion(m - 1);
            }
        }

public static void jiaohuan()
        {
            //int i = 500;
            //int j = int.MaxValue - 10;
            ////int i = 10;
            ////int j = 20;

            //Console.WriteLine("i={0},j={1}", i, j);

            //i = i + j;//i=30
            //j = i - j;//j=10;
            //i = i - j;//i=20; 
            int m = 9;
            int n = 5;
            Console.WriteLine("初始值");
            Console.WriteLine(m);
            Console.WriteLine(n);
            Console.WriteLine("中间变化");
            m = m ^ n;
            Console.WriteLine(m);
            n = n ^ m;
            Console.WriteLine(n);
            m = m ^ n;
            Console.WriteLine("交换过的值");
            Console.WriteLine(m);
            Console.WriteLine(n);
        }

#region 基类继承，重写问题
    public class Fruit
    {

        public Fruit()
        {

            FruitName = "Fruit";

            WriteFruitName();

        }

        public virtual void WriteFruitName()
        {

            Console.WriteLine("Fruit‘s WriteFruitName(),The Name Is " + FruitName);

        }

        protected string FruitName { get; set; }

    }

    public class Banana : Fruit
    {

        public Banana()
        {

            FruitName = "Banana";
           // WriteFruitName();//在这调用和不调用两种截然不同的结果
        }

        public override void WriteFruitName()
        {

            Console.WriteLine("Banana‘s WriteFruitName(),The Name Is " + FruitName);

        }

    } 
    #endregion

 //执行结果是：Banana‘s WriteFruitName(),The Name Is Fruit。
            //原因就是调用虚方法时，发现子类覆载了该方法，所以调用Banana类的WriteFruitName，
            //但此时Banana类的构造器还没被执行，也就是说FruitName属性在Banana类中还没被赋值呢，而基类的构造器给它赋值为Fruit。
            Banana b = new Banana();
            // 执行结果是：Banana‘s WriteFruitName(),The Name Is Banana。
             b.WriteFruitName();