Var keyword in c sharp

 C# is a strongly typed language. That means you should declare variables before using it.

It can be of explicitly typed or implicitly typed. I.e when we know the data type of a variable you can explicitly typed it

Example:

Int a;

a=10;

or

int a=10;

but in case if you not aware of the data type of variable by using implicitly typed  manner.

Var keyword is used for that.

Var a=10;

The data type of the variable is the data type of value we are assigning to the variable.

In the above example 10 is int type. So a is int

Var name=”Muthu karthikeyan”;

In this example “ Muthu karthikeyan” is string so the data type of name is String.

The variable declared using var keyword is strongly typed. You cannot change the type of variable after declaring it.

Example:

var a =10;

a=”karthikeyan”;

The above statement will throw An error that a is int type. You cannot assign string value to integer variable.

Don’t use var keyword for declaring data type of a property and also return type of method.

Var keyword is use full  in case of linq query where we don’t know the data type that the query will return.

Example:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace ConsoleApp1

{

    class Program

    {

        static void Main(string[] args)

        {

            string[] arr = { "muthu", "karthikeyan", "vishnu", "pradeep" };

            var o = from a in arr where a.Length > 5 select new { len = a.Length, value = a };

            foreach(var v in o)

            {

                Console.WriteLine("name={0} length={1}", v.value, v.len);

            }

            Console.ReadKey();

            // Go to http://aka.ms/dotnet-get-started-console to continue learning how to build a console app!

        }

    }

}

Output:

name=karthikeyan length=11

name=vishnu length=6

name=pradeep length=7

in the above case var keyword is very usefull.

-Muthu karthikeyan.

Madurai.