C# IEnumerable

• IEnumerable is an interface.
• It is returned from query expressions.
• It implements the GetEnumerator method.
• It enables the facility to use foreach-loop.
• It permits the use of extension methods in the System.Linq namespace.
• ToList and ToArray conversion is possible to an IEnumerable instance.
   

In the following example the Display method accepts a list of names as arguments and displays them in the Console

 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

 

 

 

class Program

{

    static void Main()

    {

            Display(new List<string> { "Anu", "James", "Sam" });

    }

 

    static void Display(IEnumerable<string> names)

    {

            foreach (string value in names)

                Console.WriteLine(value);

    }

}

 

 

The same example is modified to accept a list of array values as arguments

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using IEnuExample1;

 

 

 

class Program

{

    static void Main()

    {

        string[] names = new string[] { "Anu", "James", "Sam" };

 

        Display(names);

 

 

    }

 

    static void Display(IEnumerable<string> namesArg)

    {

            foreach (string value in namesArg)

                Console.WriteLine(value);

    }

}

 

The following example  convert object data into a List instance:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

 

namespace EnumEx2

{

  

 

class Program

{

    static void Main()

    {

                    //

                    // Use this input string[] array.

                    // ... Convert it to a List with the ToList extension.

                    //

                    string[] array = new string[]

                    {

                        "Anu", "James", "Sam"

                    };

                    List<string> list = array.ToList();

                    //

                    // Display the list.

                    //

          

 

                    foreach (string value in list)

                    {

                        Console.WriteLine(value);

                    }

    }

}

 

}

 

The following example sorts names using the LINQ syntax and displays these sorted elements in an array variable:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

 

namespace EnumExample3

{

 

 

    class Program

    {

        static void Main()

        {

            //

            // Use this input string[] array.

            // ... Convert it to a List with the ToList extension.

            //

            string[] array = new string[]

                    {

                        "James", "Sam", "Anu"

                    };

 

            // Use query expression on array.

            //

            var query = from element in array

                        orderby element

                        select element;

 

            Console.WriteLine(array.Count());

 

            string[] array2 = query.ToArray();

            //

            // Display array.

            //

            foreach (string value in array2)

            {

                Console.WriteLine(value);

            }

 

        }

    }

 

}