What is the use of Indexers in C# and How to create one.

Aarti Gupta

5y749Learn iOS Programming

What is the use of Indexers in C# and How to create one?

3 Replies

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Sachin Singh5y ago
Accepted answer
Though there are multiple uses , i will go with one and the biggest ,
suppose there is an Employee and He has 4 addresses , now you want to fetch his address as index like .Net framework has many methods which gives you the freedom to get things by index
for example consider Ado.Net Connection string
String cs=ConfigurationManager.ConnectionStrings["myCs"].ConnectionString;
here the Ado.Net developers has implemented the ConnectionString as an Index for our ease.
so, the easiest way to remember it is , if you have collection of things inside a class then you can implement indexes which is far better than a normal method.
Lets come to our example of employee has 4 addresses.
class Program
   {
       static void Main(string[] args)
       {
           List emps = new List();
           Employee e1 = new Employee();
           e1.Name = "ram";
           e1.Id = 1;
           List add1 = new List();
           Adress add = new Adress();
           add.city = "bbsr";
           add.street = "delta";
           add1.Add(add);
           e1.addresses=add1;

           Console.WriteLine(e1["delta"]);
       }
   }

   public class Employee
   {
       List lstaddress = new List();

       public int Id { get; set; }
       public string Name { get; set; }

       public List addresses
       {
           get
           {
               return lstaddress;
           }

           set
           {
               lstaddress = value;
           }
       }

       public string this[string street]
       {
           get
           {

               return addresses.FirstOrDefault(x => x.street == street).city;
           }
       }
   }

   public class Adress
   {


       public string street { get; set; }

       public string city { get; set; }
   }
As you can see , we are now able to fetch his City based on Street as index.
In short Indexers enables us to create a method by which we can fetch something as an array element.
Cheers.
+2
Aarti Gupta5y ago
Thanks @Sachin and @Rajnikant , Both have given in-depth definition ,Thanks.
0
Rajanikant Hawaldar5y ago
Indexers are elements in a C# program that allow a Class to behave as an Array. You would be able to use the entire class as an array. In this array you can store any type of variables. The variables are stored at a separate location but addressed by the class name itself.

How to create indexers in C# check below code
using System;

namespace IndexerApplication {



   class IndexedNames {

      private string[] namelist = new string[size];

      static public int size = 10;



      public IndexedNames() {

         for (int i = 0; i < size; i++)

         namelist[i] = "N. A.";

      }

      public string this[int index] {

         get {

            string tmp;



            if( index >= 0 && index <= size-1 ) {

               tmp = namelist[index];

            } else {

               tmp = "";

            }



            return ( tmp );

         }

         set {

            if( index >= 0 && index <= size-1 ) {

               namelist[index] = value;

            }

         }

      }

      static void Main(string[] args) {

         IndexedNames names = new IndexedNames();

         names[0] = "Zara";

         names[1] = "Riz";

         names[2] = "Nuha";

         names[3] = "Asif";

         names[4] = "Davinder";

         names[5] = "Sunil";

         names[6] = "Rubic";



         for ( int i = 0; i < IndexedNames.size; i++ ) {

            Console.WriteLine(names[i]);

         }

         Console.ReadKey();

      }

   }

}
For more info.

https://www.c-sharpcorner.com/blogs/how-to-create-indexer-in-c-sharp1
0