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Computer Programming : Nullable types, Null coalescing operator in c# Programming

In Computer Programming, C# Data types are divided into two broad categories such as Value types and Reference type. In Value types, some inbuilt types such as int, float, double, structs, enum etc. These all are non-nullable types, it means these types don't hold null value. In other hand Reference types such as string, Interface, Class, delegates, arrays etc. can hold null value.
By default value types are non nullable. To make them nullable use, programmer have to use ?
  • int a=0   a is non nullable, so a cannot be set to null, a=null will generate compiler error
  • int ?b=0  b is nullable int, so b=null is legal

Operator Need

If programmer want to assign null value to non-nullable data types then there are some operators explained with an example. 

Lets take an simple example

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int a;
            int? b = 100;
            a = b ?? 0;
            System.Console.WriteLine(a);
            Console.ReadKey();
        }
    }
}
Computer Programming : Nullable types, Null coalescing operator in c# Programming

Output show that if b hold some value like 100 then Null coalescing operator assign value to variable (a). If b hold null value then Null coalescing operator assign default value, which is zero to variable a. 

Replace the declaration of variable b with the following line:
            int? b = Null;
This will outputs zero (default value).

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Memory representation of Linked List

             In memory the linked list is stored in scattered cells (locations).The memory for each node is allocated dynamically means as and when required. So the Linked List can increase as per the user wish and the size is not fixed, it can vary.

               Suppose first node of linked list is allocated with an address 1008. Its graphical representation looks like the figure shown below:


      Suppose next node is allocated at an address 506, so the list becomes,



  Suppose next node is allocated with an address with an address 10,s the list become,


The other way to represent the linked list is as shown below:




 In the above representation the data stored in the linked list is “INDIA”, the information part of each node contains one character. The external pointer root points to first node’s address 1005. The link part of the node containing information I contains 1007, the address of next node. The last node …