C # basic -- Indexer

The indexer syntax facilitates the creation of client applications as classes, structures, or interfaces for array access.

The indexer is mainly used to encapsulate internal sets or arrays. Use the this keyword.

1. class TempRecord{    private float[] temps=new float[10]{56.2F, 56.7F, 56.5F, 56.9F, 58.8F,                                             61.3F, 65.9F, 62.1F, 59.2F, 57.5F};    public int Length    {        get{return temps.Length;}    }        public float this[int index]    {        get{return temps[index];}        set {temps[index]=value;}    }}public class MyClass{    public static void Main()    {        TempRecord tempRecord=new TempRecord();        tempRecord[3]=58.3F;        tempRecord[5]=60.1F;              for(int i=0;i<tempRecord.Length;i++)        {            Console.WriteLine("Element #{0} = {1}", (i+1), tempRecord[i]);        }               Console.ReadLine();    }}

Output:

 

C # The Index type is not limited to integers:

1. class DayCollection{    string [] days={ "Sun", "Mon", "Tues", "Wed", "Thurs", "Fri", "Sat" };    private int GetDay(string testDay)    {        int i = 0;        foreach (string day in days)        {            if (day == testDay)            {                return i;            }            i++;        }        return -1;    }    public int this[string day]    {        get{return (GetDay(day));}    }}public class Program{    public static void Main()    {        DayCollection week=new DayCollection();        Console.WriteLine(week["Fri"]);        Console.WriteLine(week["Made-up Day"]);        Console.ReadLine();    }}

Output:

 

Use the indexer on the interface:

1. public interface IIndexInterface{    int this[int index]    {        get;        set;    }}class IndexClass:IIndexInterface{    public int [] arr=new int[100];    public int this[int index]    {        get        {            if (index < 0 || index >= 100)            {                return 0;            }            else            {                return arr[index];            }        }        set        {            if (!(index < 0 || index >= 100))            {                arr[index] = value;            }        }    }}public class Program{    public static void Main()    {        IndexClass test=new IndexClass();        test[2]=4;        test[5]=32;        for(int i=0;i<10;i++)        {            Console.WriteLine("Element #{0} = {1}", i, test[i]);        }        Console.ReadLine();   }}

Output: