实验5-1

B.

(1)当装入水果超过10个时,会抛出异常:索引超过了数组界限

解决方法:修改程序在加入前比较水果篮中数目是否已经为10,若未达到则继续添加,若水果数量达到十个时,则停止添加,并弹出篮子已满的警告.

修改程序如下:

using System;

namespace test5_1_1
{
    public class Fruit
    {
        public virtual string Name
        {
            get
            {
                return ("Fruit");
            }
        }

        public static int length { get; set; }
    }
    public class Apple : Fruit
    {
        public override string Name
        {
            get
            {
                return ("Apple");
            }
        }
    }
    public class Banana : Fruit
    {
        public override string Name
        {
            get
            {
                return ("Banana");
            }
        }
    }
    public interface IEnumerable
    {
        IEnumerator GetEnumerator();
    }
    public interface IEnumerator
    {
        object Current
        {
            get;
        }
        bool MoveNext();
        void Reset();
    }
    public class FruitBasket : IEnumerable
    {
        static int Max = 10;
        Fruit[] basket = new Fruit[Max];
        int a = Fruit.length;
        public static int count = 0;
        internal Fruit this[int index]
        {
            get
            {
                return (basket[index]);
            }
            set
            {
                basket[index] = value;
            }
        }
        internal int Count
        {
            get
            {
                return (count);
            }
        }
        public void Add(Fruit fruit)
        {
            if (count >= Max)
            {
                Console.WriteLine("超出水果筐容量！");
            }
            basket[count++] = fruit;
        }
        public IEnumerator GetEnumerator()
        {
            return (new FruitBasketEnumerator(this));
        }
    }
    public class FruitBasketEnumerator : IEnumerator
    {
        FruitBasket fruitBasket;
        int index;
        public void Reset()
        {
            index = -1;
        }
        public object Current
        {
            get
            {
                return (fruitBasket[index]);
            }
        }
        public bool MoveNext()
        {
            if (++index >= fruitBasket.Count)
                return false;
            else
                return true;
        }
        internal FruitBasketEnumerator(FruitBasket fruitBasket)
        {
            this.fruitBasket = fruitBasket;
            Reset();
        }
    }
    class CollectionsExample
    {
        static void Main(string[] args)
        {
            int a = 0;
            int b = 0;
            FruitBasket fruitBasket = new FruitBasket();
            for (int i = 0; i < 2; i++)
            {
                if (FruitBasket.count <= 10)
                {
                    Console.WriteLine("Adding a Banana");
                    fruitBasket.Add(new Banana());
                    a = i + 1;
                }
                else
                {
                    break;
                }
            }
            for (int j = 0; j < 7; j++)
            {
                if (FruitBasket.count <= 9)
                {
                    Console.WriteLine("Adding an Apple");
                    fruitBasket.Add(new Apple());
                    b = j + 1;
                }
                else
                {
                    break;
                }
            }
            if (a + b == 10)
            {
                Console.WriteLine("水果篮容量已到达上限！");
            }
            Console.WriteLine();
            Console.WriteLine("The basket is holding!");
            Console.WriteLine(a + "  Apple(s)");
            Console.WriteLine(b + "  Banana(s)");
            Console.Read();
        }
    }
}

运行结果如下:

• 未达到10个时,香蕉两个,苹果七个

• 总数达到10个时,香蕉四个,苹果六个

(2)在水果篮中加入橙子

实验代码:

using System;

namespace test5_1_2
{
    public class Fruit
    {
        public virtual string Name
        {
            get
            {
                return ("Fruit");
            }
        }

        public static int length { get; set; }
    }
    public class Apple : Fruit
    {
        public override string Name
        {
            get
            {
                return ("Apple");
            }
        }
    }
    public class Banana : Fruit
    {
        public override string Name
        {
            get
            {
                return ("Banana");
            }
        }
    }
    public class Orange : Fruit
    {
        public override string Name
        {
            get
            {
                return ("Orange");
            }
        }
    }
    public interface IEnumerable
    {
        IEnumerator GetEnumerator();
    }
    public interface IEnumerator
    {
        object Current
        {
            get;
        }
        bool MoveNext();
        void Reset();
    }
    public class FruitBasket : IEnumerable
    {
        static int Max = 10;
        Fruit[] basket = new Fruit[Max];
        int a = Fruit.length;
        public static int count = 0;
        internal Fruit this[int index]
        {
            get
            {
                return (basket[index]);
            }
            set
            {
                basket[index] = value;
            }
        }
        internal int Count
        {
            get
            {
                return (count);
            }
        }
        public void Add(Fruit fruit)
        {
            if (count >= Max)
            {
                Console.WriteLine("超出水果筐容量！");
            }
            basket[count++] = fruit;
        }
        public IEnumerator GetEnumerator()
        {
            return (new FruitBasketEnumerator(this));
        }
    }
    public class FruitBasketEnumerator : IEnumerator
    {
        FruitBasket fruitBasket;
        int index;
        public void Reset()
        {
            index = -1;
        }
        public object Current
        {
            get
            {
                return (fruitBasket[index]);
            }
        }
        public bool MoveNext()
        {
            if (++index >= fruitBasket.Count)
                return false;
            else
                return true;
        }
        internal FruitBasketEnumerator(FruitBasket fruitBasket)
        {
            this.fruitBasket = fruitBasket;
            Reset();
        }
    }
    class CollectionsExample
    {
        static void Main(string[] args)
        {
            int a = 0;
            int b = 0;
            int c = 0;
            FruitBasket fruitBasket = new FruitBasket();
            for (int i = 0; i < 3; i++)
            {
                if (FruitBasket.count <= 10)
                {
                    Console.WriteLine("Adding a Banana");
                    fruitBasket.Add(new Banana());
                    a = i + 1;
                }
                else
                {
                    break;
                }
            }
            for (int j = 0; j < 3; j++)
            {
                if (FruitBasket.count <= 9)
                {
                    Console.WriteLine("Adding an Apple");
                    fruitBasket.Add(new Apple());
                    b = j + 1;
                }
                else
                {
                    break;
                }
            }
            for (int k = 0; k < 3; k++)
            {
                if (FruitBasket.count <= 9)
                {
                    Console.WriteLine("Adding an Oange");
                    fruitBasket.Add(new Orange());
                    c = k + 1;
                }
                else
                {
                    break;
                }
            }
            if (a + b + c == 10)
            {
                Console.WriteLine("水果篮容量已到达上限！");
            }
            Console.WriteLine();
            Console.WriteLine("The basket is holding!");
            Console.WriteLine(a + "  Apple(s)");
            Console.WriteLine(b + "  Banana(s)");
            Console.WriteLine(c + "  Orange(s)");
            Console.Read();
        }
    }
}

实验结果:

• 未达到10个,三种水果各三个

• 超过十个,香蕉三个,苹果两个,橙子六个