C#之泛型使用 IEnumerable

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using System;using System.Collections;using System.Collections.Generic;using System.Text;using System.Linq;namespace ss{    public class LinkListNode  //链表节点    {        public object Value;    //节点内容        public LinkListNode(object node)   //构造函数        {            this.Value = node;        }        public LinkListNode next;    //指向后继节点        public LinkListNode prev;   //指向前驱节点    }    public class LinkList : IEnumerable    {        public LinkListNode first;    //链表的第一个节点指针        public LinkListNode last;     //链表的最后一个节点指针        public LinkListNode AddLast(object node)  //添加一个节点        {            var newNode = new LinkListNode(node);            if (first == null)            {                first = newNode;                last = first;            }            else            {                last.next = newNode;                newNode.prev = last;                last = newNode;            }            return newNode;        }        public IEnumerator GetEnumerator()        {            LinkListNode temp = first;            while (temp != null)            {                yield return temp.Value;                temp = temp.next;            }        }    }    class Program    {        static void Main()        {            LinkList list1 = new LinkList();            list1.AddLast(1);            list1.AddLast(2);            list1.AddLast(3);            foreach (int i in list1)            {                Console.WriteLine(i);            }        }    }}

using System;using System.Collections;using System.Collections.Generic;using System.Text;using System.Linq;namespace ss{    public class LinkListNode<T>    {        public T Value;    //节点值        public LinkListNode<T> next;  //后继节点指针        public LinkListNode<T> prev;  //前驱节点指针        public LinkListNode(T value)  //构造函数        {            this.Value = value;        }    }    public class LinkList<T> : IEnumerable<T>    {        public LinkListNode<T> first;        public LinkListNode<T> last;        public LinkListNode<T> AddLast(T node)        {            LinkListNode<T> newNode = new LinkListNode<T>(node);            if (first == null)  //此链表无内容            {                first = newNode;                last = first;            }            else            {                last.next = newNode;                newNode.prev = last;                last = newNode;            }            return newNode;        }        public IEnumerator<T> GetEnumerator()        {            LinkListNode<T> current = first;            while (current != null)            {                yield return current.Value;                current = current.next;            }        }        IEnumerator IEnumerable.GetEnumerator()        {            return GetEnumerator();        }    }    class Program    {        static void Main()        {            LinkList<int> list1 = new LinkList<int>();            list1.AddLast(1);            list1.AddLast(2);            list1.AddLast(3);            list1.AddLast(4);            foreach (int i in list1)            {                Console.WriteLine(i);            }        }    }}

//泛型 约束 默认综合运用using System;using System.Collections;using System.Collections.Generic;using System.Text;using System.Linq;namespace ss{    // *********************************文档定义    public interface IDocument       //定义一个借口    {        string Title { get; set; }        string Content { get; set; }    }    public class Document : IDocument     {        public string Title { get; set; }      //实现借口        public string Content { get; set; }    //实现借口        public Document(string title,string content) //构造函数        {            this.Title=title;            this.Content=content;        }    }    //***************************    public class DocumentManager<T> where T:IDocument     //T为文档类型  并且T必须实现IDocument接口    {        private readonly Queue<T> documentQueue = new Queue<T>();   //建立一个泛型队列        public void AddDocument(T doc)  //添加一个文档        {            lock (this)            {                documentQueue.Enqueue(doc);            }        }        public bool IsDocuementAvailable   //字段        {            get { return documentQueue.Count > 0; }        }        public T GetDocument()   //获取文档        {            T doc = default(T); //默认值            lock (this)            {                doc = documentQueue.Dequeue();            }            return doc;        }        public void DisplayAllDocuments()   //展示文档Title属性        {            foreach (T doc in documentQueue)            {                Console.WriteLine(((IDocument)doc).Title);            }        }    }    class Program    {        static void Main()        {            DocumentManager<Document> dm = new DocumentManager<Document>();            dm.AddDocument(new Document("Title A", "Sample A")); //添加文档            dm.AddDocument(new Document("Title B", "Sample B"));            dm.DisplayAllDocuments();  //展示文档            if (dm.IsDocuementAvailable)            {                Document d = dm.GetDocument();  //获取一个文档，即出栈一个元素                Console.WriteLine(d.Content);            }        }    }}

泛型接口的协变和抗变

//泛型 约束 默认综合运用using System;using System.Collections;using System.Collections.Generic;using System.Text;using System.Linq;namespace ss{    public class Shape      //基类    {        public double width;  //宽        public double height;  //高        public override string ToString()        {            return String.Format("width:{0},Height:{1}", width, height);        }    }    public class Rectangle : Shape       //子类    {        public double Area()       //计算面积        {            return width * height;        }    }    public interface IIndex<out T>       //泛型接口    {        T this[int index] { get; }        int Count { get; }    }    public interface IDisplay<in T>    {        void Show(T item);    }    public class RectangleCollection : IIndex<Rectangle>    //注：协变 子类    {        private Rectangle[] data = new Rectangle[3]        {            new Rectangle{height=2,width=5},            new Rectangle{height=3,width=7},            new Rectangle{height=4.5,width=2.9}        };        public static RectangleCollection GetRectangles()        {            return new RectangleCollection();        }        public Rectangle this[int index]       //实现泛型接口中的内容        {            get             {                if (index < 0 || index > data.Length)                {                    throw new ArgumentOutOfRangeException("index");                }                return data[index];            }        }        public int Count         //实现泛型接口中的内容        {            get             {                return data.Length;            }        }    }    public class ShapeDisplay : IDisplay<Shape>    //注：抗变 父类    {        public void Show(Shape s)        {            Console.WriteLine("{0}width:{1},Height:{2}", s.GetType().Name, s.width, s.height);        }    }    class Program    {        static void Main()        {           IIndex<Rectangle> rectangles = RectangleCollection.GetRectangles();            IIndex<Shape> shapes = rectangles;        //将多种多样的子类赋给父类，通过父类来输出子类的信息            for (int i = 0; i < shapes.Count; i++)    //通过此种方法可以通过父类来确定是哪个子类            {                Console.WriteLine(shapes[i]);            }           //IDisplay<Shape> shapeDisplay = new ShapeDisplay();           //IDisplay<Rectangle> rectangleDisplay = shapeDisplay;           //rectangleDisplay.Show(rectangles[0]);        }    }}

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