Nullable Types in .NET

 Introduction

 

Today, in this blog let's play around with one of the interesting and most useful concept in C#.

 

Question: What is nullable type?

In simple terms "It provides flexibility for us to define null values to non-accepting datatypes".

Step 1: Create a new webform project
 

Image1.jpg

 

Step 2: The complete code of webform1.aspx looks like this:

 

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="NullableTypesApp.WebForm1" %>

 

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head id="Head1" runat="server">

    <title></title>

</head>

<body>

    <form id="form1" runat="server">

    <center>

        <div>

            <table>

                <tr>

                    <td colspan="2">

                        <asp:Label ID="Label1" runat="server" Text="Nullable Types in .NET" Font-Bold="true"

                            Font-Size="Large" Font-Names="Verdana" ForeColor="Maroon"></asp:Label>

                    </td>

                </tr>

                <tr>

                    <td colspan="2" align="center">

                        <asp:Button ID="Button1" runat="server" Text="Addition" Font-Names="Verdana" Width="213px"

                            BackColor="Orange" Font-Bold="True" OnClick="Button1_Click" />

                    </td>

                </tr>

                <tr>

                    <td colspan="2" align="center">

                        <asp:Button ID="Button2" runat="server" Text="Substraction" Font-Names="Verdana"

                            Width="213px" BackColor="Orange" Font-Bold="True" OnClick="Button2_Click" />

                    </td>

                </tr>

                <tr>

                    <td colspan="2" align="center">

                        <asp:Button ID="Button3" runat="server" Text="Multiplication" Font-Names="Verdana"

                            Width="213px" BackColor="Orange" Font-Bold="True" OnClick="Button3_Click" />

                    </td>

                </tr>

                <tr>

                    <td colspan="2" align="center">

                        <asp:Button ID="Button4" runat="server" Text="Division" Font-Names="Verdana" Width="213px"

                            BackColor="Orange" Font-Bold="True" OnClick="Button4_Click" />

                    </td>

                </tr>

                <tr>

                    <td colspan="2" align="center">

                        <asp:Label ID="Label5" runat="server" Font-Bold="true" Font-Names="Verdana" ForeColor="Maroon"></asp:Label>

                    </td>

                </tr>

            </table>

        </div>

    </center>

    </form>

</body>

</html>

 

Step 3: The complete code of webform1.aspx.cs looks like this:

 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace NullableTypesApp

{

    public partial class WebForm1 : System.Web.UI.Page

    {

        protected void Page_Load(object sender, EventArgs e)

        {

        }

        double? a = null;double? b = null;

        protected void Button1_Click(object sender, EventArgs e)

        {

            //a = 10;

            //b = 20;

            if(a.HasValue == true && b.HasValue == true)

            {

                Label5.Text = "Addition Result is: " + (a + b);

                Label5.ForeColor = System.Drawing.Color.Green;

            }

            else

            {

                Label5.Text = "Values are null";

                Label5.ForeColor = System.Drawing.Color.Red;

            }

        }

        protected void Button2_Click(object sender, EventArgs e)

        {

            //a = 20;

            //b = 10;

            if (a.HasValue && b.HasValue)

            {

                Label5.Text = "Substraction Result is: " + (a - b);Label5.ForeColor = System.Drawing.Color.Green;

            }

            else

            {

                Label5.Text = "Values are null";

                Label5.ForeColor = System.Drawing.Color.Red;

            }

        }

        protected void Button3_Click(object sender, EventArgs e)

        {

            //a = 10;//b = 20;

            if (a.HasValue && b.HasValue)

            {

                Label5.Text = "Multiplication Result is: " + (a * b);

                Label5.ForeColor = System.Drawing.Color.Green;

            }

            else

            {

                Label5.Text = "Values are null";

                Label5.ForeColor = System.Drawing.Color.Red;

            }

        }

        protected void Button4_Click(object sender, EventArgs e)

        {

            //a = 10;//b = 20;

            if (a.HasValue && b.HasValue)

            {

                Label5.Text = "Division Result is: " + (a / b);

                Label5.ForeColor = System.Drawing.Color.Green;

            }

            else

            {

                Label5.Text = "Values are null";

                Label5.ForeColor = System.Drawing.Color.Red;

            }

        }

    }

}

 

Step 4: The output of the application looks like this

Image2.jpg

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