What is as keyword in C#

Introduction

In C#, as operator is like a cast operation, which performs only reference conversion, nullable conversion and boxing conversion. as keyword can not be perform to other conversion such as user define conversion.

Example

using System;

 

namespace as_keyword_in_c_sharp

{

    class c1  // create class c1

    {

    }

    class c2  //create another class c2,which is return type is string

    {

        public string show(string str)

        {

            return str;

        }

    }

   

    class Program

    {

        static void Main(string[] args)

        {

            c1 obj1 = new c1(); //create object of class c1

            c2 obj2 = new c2(); //create object of class c2

 

            object[] obj_array = new object[6]; //create object type array

                       

            object a= 123;        //create object type variable, which is value is int type

            object b = "welcome"; //create object type variable, which is value is string type

            object c = 10.05;     //create object type variable, which is value is double type

            object d = null;     //create object type variable, which is value is null type

 

            //store object type value in object type array

            obj_array[0] = obj1; 

            obj_array[1] = obj2.show("hello");

            obj_array[2] = a;

            obj_array[3] = b;

            obj_array[4] = c;

            obj_array[5] = d;

 

            for (int k = 0; k < obj_array.Length; k++)

            {

                Console.Write(" {0} : ", k);

                // conversion of object type value to string type through as keyword

                string str = obj_array[k] as string;

 

                if (str != null)

                {

                    Console.WriteLine("'" + str + "'");

                }

                else

                 {

                   Console.WriteLine("No string");

                 }

            }

            Console.ReadLine();

        }

    }

}

Output

output.jpg

Ebook Download
View all
Learn
View all