nullable types in c sharp Arabic #05

Part 05 - C# Tutorial - Nullable Types

Suggested Videos
Part 02 - Built-in types
Part 03 - String type
Part 04 - Operators

In this video, we will discuss
1. Nullable types in C#
2. Null Coalescing Operator ??

In C# types are divided into 2 broad categories.
Value Types - int, float, double, structs, enums etc
Reference Types – Interface, Class, delegates, arrays etc.

By default value types are non nullable. To make them nullable use ?
int i = 0 (i is non nullable, so "i" cannot be set to null, i = null will generate compiler error)
int? j = 0 (j is nullable int, so j=null is legal)

Nullable types bridge the differences between C# types and Database types

Program without using NULL coalescing operator
using System;
class Program
{
  static void Main()
{
  int AvailableTickets;
  int? TicketsOnSale = null;

  if (TicketsOnSale == null)
{
AvailableTickets = 0;
}
  else
{
AvailableTickets = (int)TicketsOnSale;
}

  Console.WriteLine("Available Tickets={0}", AvailableTickets);
}
}

The above program is re-written using NULL coalescing operator
using System;
class Program
{
  static void Main()
{
  int AvailableTickets;
  int? TicketsOnSale = null;

  //Using null coalesce operator ??
AvailableTickets = TicketsOnSale ?? 0;

  Console.WriteLine("Available Tickets={0}", AvailableTickets);
}
}

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