• <ins id="pjuwb"></ins>
    <blockquote id="pjuwb"><pre id="pjuwb"></pre></blockquote>
    <noscript id="pjuwb"></noscript>
          <sup id="pjuwb"><pre id="pjuwb"></pre></sup>
            <dd id="pjuwb"></dd>
            <abbr id="pjuwb"></abbr>

            C++ Programmer's Cookbook

            {C++ 基礎(chǔ)} {C++ 高級(jí)} {C#界面,C++核心算法} {設(shè)計(jì)模式} {C#基礎(chǔ)}

            Implementing IEnumerator and IEnumerable Interfaces using Inner Class in C#(very good)

            .NET framework provides IEnumerable and IEnumerator interfaces to implement collection
            like behavior to user defined classes. A
            developer can implement these interfaces to?
            provide collection like behavior to their classes. These interfaces are implemented?
            through inner classes.

            An inner class ( also known as Nested Type ) is a class which is enclosed inside
            another class.

            class A
            {
            int i ;
            class B // Class B is a inner class or Nested Type?
            {
            }
            }?

            IEnumerator and IEnumerable interfaces are defined in System.Collections namespace as :

            public interface IEnumerable
            {
            IEnumerator GetEnumerator(); //Returns a Enumerator
            }

            public interface IEnumerator
            {
            bool MoveNext(); //An enumerator is always positioned before the?
            //first element of the collection, first call to MoveNext?
            //moves the enumerator over the first element of the
            //collection?

            object Current { get ; } //Returns current object from the collection

            void Reset(); //Resets enumerator to just above the first element of the collection.
            }?

            For more details about above interfaces, refer
            Microsoft .NET framework documentation.

            Above two interfaces must be implemented to provide a collection (similar to ArrayList ) like
            behavior to user defined classes. There is one more interface called Collection interface?
            which I am excluding from our discussion.

            To demonstrate the working of above interfaces and inner class I have created a class called
            ItemCollection which implements IEnumerable interface.

            Within ItemCollection class there is one more class ( inner class or Nested Type ) called
            ItemIterator which implements IEnumerator interface. ItemCollection class also contains a?
            string array itemId, which provides the basis for iteration.?

            For implementation details, see the code below and follow these steps :

            1. Create a file ItemCollection.cs and save the source in that.

            //File ItemCollection.cs
            using System;
            using System.Collections;?

            //Class ItemCollection implements IEnumerable interface
            class ItemCollection : IEnumerable
            {
            String[] itemId ;

            //Constructor to create and populate itemId String array
            public ItemCollection( int noOfItem )
            {
            itemId = new String[noOfItem] ;
            for(int i = 0; i < itemId.Length; i ++ )
            {
            itemId[i] = i.ToString();
            }
            }

            //Implementation of method GetEnumerator of IEnumerable interface
            public virtual IEnumerator GetEnumerator()
            {
            return new ItemIterator(this);
            }


            //Inner class ItemIterator, implements IEnumerator
            public class ItemIterator : IEnumerator
            {
            //Declare a variable of type ItemCollection,
            //to keep reference to enclosing class instance
            private ItemCollection itemCollection;

            //Declare a integer pointer and Set to -1, so that
            //first call to MoveNext moves the enumerator over?
            //the first element of the collection.
            private int index = -1 ;


            //Pass an instance of enclosing class
            public ItemIterator(ItemCollection ic)
            {
            //Save enclosing class reference?
            itemCollection = ic ;
            }

            //After an enumerator is created or after a Reset,
            //an enumerator is positioned before the first element
            //of the collection, and the first call to MoveNext?
            //moves the enumerator over the first element of the
            //collection.

            public bool MoveNext()
            {
            index++ ;
            if( index < itemCollection.itemId.Length )
            {
            return true ;
            }
            else
            {
            index = -1;
            return false;
            }
            }

            //Return the current object, in our case Item Id string?
            //from itemId[] array. Throws InvalidOperationException exception
            //if index pointing to wrong position
            public object Current
            {
            get
            {
            if( index <= -1 )?
            {
            throw new InvalidOperationException() ;
            }
            return itemCollection.itemId[index];
            }
            }

            //Reset pointer to -1
            public void Reset()
            {
            index = -1;
            }

            }

            public static int Main(String[] args)
            {
            //Instantiate the collection
            ItemCollection itemCol = new ItemCollection(10);

            //Iterate the collection with various looping construct
            //provided in c#
            Console.WriteLine("1. Iteration using foreach loop:");
            foreach( String itemIdStr in itemCol)
            {
            Console.Write(itemIdStr + " " );
            }

            Console.WriteLine("\n\n2. Iteration using for loop:");
            for(IEnumerator ie = itemCol.GetEnumerator() ;
            ie.MoveNext();)
            {
            Console.Write(ie.Current + " " );
            }

            Console.WriteLine("\n\n3. Iteration using while loop:");
            IEnumerator ie1 = itemCol.GetEnumerator();
            while(ie1.MoveNext())
            {
            Console.Write(ie1.Current + " ");
            }
            return 0;
            }

            }


            2. Compile the above code as

            csc ItemCollection.cs

            3. Run the file ItemCollection.exe to see following output in console window :

            1. Iteration with foreach loop:
            0 1 2 3 4 5 6 7 8 9

            2. Iteration with for loop:
            0 1 2 3 4 5 6 7 8 9

            3. Iteration with while loop:
            0 1 2 3 4 5 6 7 8 9



            posted on 2006-04-11 12:04 夢(mèng)在天涯 閱讀(891) 評(píng)論(0)  編輯 收藏 引用 所屬分類: C#/.NET

            公告

            EMail:itech001#126.com

            導(dǎo)航

            統(tǒng)計(jì)

            • 隨筆 - 461
            • 文章 - 4
            • 評(píng)論 - 746
            • 引用 - 0

            常用鏈接

            隨筆分類

            隨筆檔案

            收藏夾

            Blogs

            c#(csharp)

            C++(cpp)

            Enlish

            Forums(bbs)

            My self

            Often go

            Useful Webs

            Xml/Uml/html

            搜索

            •  

            積分與排名

            • 積分 - 1808261
            • 排名 - 5

            最新評(píng)論

            閱讀排行榜

            无码乱码观看精品久久| 久久久久久久久久久久久久| 97久久香蕉国产线看观看| 亚洲国产精品18久久久久久| 91精品国产9l久久久久| 青青青青久久精品国产| 久久精品无码一区二区app| 狠狠综合久久AV一区二区三区| 久久精品人人槡人妻人人玩AV | 欧美与黑人午夜性猛交久久久| 亚洲第一永久AV网站久久精品男人的天堂AV | 思思久久99热只有频精品66| 国内精品久久久久影院薰衣草| 91精品国产91久久久久久青草| 蜜桃麻豆WWW久久囤产精品| 亚洲国产成人久久精品影视| 亚洲国产日韩欧美久久| 久久亚洲高清观看| 老色鬼久久亚洲AV综合| 一本一本久久a久久精品综合麻豆| 国产精品久久久天天影视| 无码精品久久久久久人妻中字| 久久久久无码精品| 91精品国产高清久久久久久91 | 亚洲国产精品久久久久婷婷软件 | 精品久久久久久国产| 久久www免费人成看片| 欧美国产精品久久高清| 国产精品久久久99| 99久久婷婷国产综合精品草原| 久久久无码人妻精品无码| 久久天堂AV综合合色蜜桃网| 久久精品国产久精国产一老狼| 欧美久久亚洲精品| 久久99精品久久久久久野外| 国产—久久香蕉国产线看观看| 热99re久久国超精品首页| 国产亚洲欧美精品久久久| 丁香五月网久久综合| 久久精品中文字幕久久| 国产精品伦理久久久久久|