Introduction to var datatype in C#

[khaled ahmed]

var Type:
• 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 :
• 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:
Ualue is : 1
Ualue is : 2
Ualue is : 3
Ualue is : 4
Ualue is : 5
Ualue is : 6
Ualue is : 7
Ualue is : 8
Ualue is : 9
Ualue is : 10
Sum of array elements is : 55