Introduction To Var Datatype In C#

Var Data Type in C#

C# 3.0 adds the interesting behavior of Declaring Local Variables Implicitly. This means that there is no need to mention the data type when declaring a variable. A local variable can be declared implicitly using the var keyword in C#.

Declaring local variables implicitly has some restrictions; the variable must be initialized to some expression that can not be null.

var a= 10;   
var z = "Rekha"; 

The primary reason for its existence is the introduction of anonymous types in C#.

Another point to stress is that variable inference does not work for class-level fields or method arguments or anywhere else other than for local variables in a method.

Advantages of Var Data Type

• Less typing with no loss of functionality
• Increases the type safety of your code. A foreach loop using an iteration variable which is typed to var will catch silently casts that are introduced with explicit types
• Makes it so you don't have to write the same name twice in a variable declaration.
• Some features, such as declaring a strongly typed anonymous type local variable, require the use of var

Example 1

using System;   
using System.Collections.Generic;   
using System.Linq;   
using System.Text;   
   
namespace Namesp1  
{   
    class Program   
    {   
        static void Main(string[] args)   
        {   
            var x = Convert.ToInt32(Console.ReadLine());   
            var y = Convert.ToInt32(Console.ReadLine());   
            Console.WriteLine("The Sum Is : " + (x + y));   
        }   
    }   
}   

Example 2

using System;   
namespace ConsoleApplication1   
{   
    class A   
    {   
        public static void Main()   
        {   
            int sum = 0;   
            int[] arr = new int[10];   
            for (int i = 0; i < 10; i++)   
            {   
                arr[i] = i;   
            }   
            foreach (var x in arr)   
            {   
                Console.WriteLine("Value is: " + x);   
                sum =sum + x;   
            }   
            Console.WriteLine("Sum of array elements is : " + sum);   
        }   
    }   
} 

Output