Using Nullable Type in .NET Framework 2.0 VB.NET/C#

Nullable Types which was introduced in the .NET framework 2.0 give the developer the option of storing null values in a Value Type variable.
This Will allow you to create an object which holds Null value.
This comes handy when you want an null value to be stored in an Object.

VB.NET CODE

        Private Name As String
        Private isWorking As Boolean
        Private sal As Nullable(Of Integer)

        Sub EnterDetails(ByVal n As String, ByVal wor As Boolean, ByVal sals As Nullable(Of Integer))
            Name = n
            isWorking = wor
            If isWorking = True Then
                sal = sals
            Else
                sal = Nothing
            End If
        End Sub

        Sub ShowDetails()
            Console.WriteLine("Name : " & Name)
            Console.WriteLine("IsWorking : " & isWorking)
            If (sal.HasValue = True) Then
                Console.WriteLine("Sal : " & sal.ToString())
            Else
                Console.WriteLine("Sal : N.A")
            End If
        End Sub

To use This class

    Sub Main()
        Dim i As New Emp

        i.EnterDetails("HEFIN", True, 124214)
        i.ShowDetails()
    End Sub

In C# we create Nullable Types by using the < > brackets.

C# Code
This Feature of .net framework 2.0 can be used to use an object of any type to hold a null value.

    class Employee
    {
        private string Name;
        private bool isWorking;
        private Nullable< int > sal;

        public void enterDetails(string na,bool Working,Nullable< int > salary)
        {
            this.Name = na;
            this.isWorking = Working;
            if (isWorking == true)
            {
                sal = salary;
            }
            else
            {
                sal = null;
            }
        }
        public void GetDetails()
        {
            Console.WriteLine("Name : " + this.Name);
            Console.WriteLine("IsWorking : " + this.isWorking);
            if (this.sal.HasValue == true)
            {
                Console.WriteLine("Salary : " + this.sal);
            }
            else
            {
                Console.WriteLine("Salary : N.A");
            }
        }
    }

Using this object in another class

    class usingNull
    {
        static void Main(string[] args)
        {
            Employee emp = new Employee();
            emp.enterDetails("HEFIN", true, 10090);
            emp.GetDetails();
            emp.enterDetails("ONEMORE", false, null);
            emp.GetDetails();
        }
    }

================================================================================
Regards Hefin Dsouza.