Create and Consume DLL in .NET

Introduction

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

Question: What is creating and consume DLL?

In simple terms "It enables to create DLL as components and use them across multiple projects".

Step 1: Create a new Class Library project

Step 2: The complete code of ArthmeticClass.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace Arthmetic

{

public class ArthmeticClass

{

public static double Add(double a, double b)

{

return a + b;

}

public static double Sub(double a, double b)

{

return a - b;

}

public static double Mul(double a, double b)

{

return a * b;

}

public static double Div(double a, double b)

{

return a / b;

}

Step 3: Create a new WebForm project

Step 4: Adding reference of DLL looks like this

Step 5: The complete code WebForm1.aspx looks like this:

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

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

</head>

<body>

<div>

<table>

<tr>

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

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

</td>

</tr>

<tr>

<td>

<asp:Label ID="Label3" runat="server" Text="Please Enter First Number" Font-Size="Large"

Font-Names="Verdana" Font-Italic="true"></asp:Label>

</td>

<td>

<asp:TextBox ID="TextBox1" runat="server" Width="120px"></asp:TextBox>

</td>

</tr>

<tr>

<td>

<asp:Label ID="Label2" runat="server" Text="Please Enter Second Number" Font-Size="Large"

Font-Names="Verdana" Font-Italic="true"></asp:Label>

</td>

<td>

<asp:TextBox ID="TextBox2" runat="server" Width="120px"></asp:TextBox>

</td>

</tr>

<tr>

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

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

</td>

</tr>

<tr>

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

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

</td>

</tr>

<tr>

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

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

</td>

</tr>

<tr>

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

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

</td>

</tr>

<tr>

<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 6: The complete code 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;

using Arthmetic;

namespace ArthmeticDLLApp

{

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

{

protected void Page_Load(object sender, EventArgs e)

{

TextBox1.Focus();

}

protected void Button1_Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

Label5.Text = "Please Enter Some Values";

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

}

else

{

Label5.Text = "Addition Result is: " + (ArthmeticClass.Add(double.Parse(TextBox1.Text), double.Parse(TextBox2.Text)));

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

TextBox1.Text = string.Empty;

TextBox2.Text = string.Empty;

}

protected void Button2_Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

Label5.Text = "Please Enter Some Values";

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

}

else

{

Label5.Text = "Substraction Result is: " + (ArthmeticClass.Sub(double.Parse(TextBox1.Text), double.Parse(TextBox2.Text)));

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

TextBox1.Text = string.Empty;

TextBox2.Text = string.Empty;

}

protected void Button3_Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

Label5.Text = "Please Enter Some Values";

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

}

else

{

Label5.Text = "Multiplication Result is: " + (ArthmeticClass.Mul(double.Parse(TextBox1.Text), double.Parse(TextBox2.Text)));

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

TextBox1.Text = string.Empty;

TextBox2.Text = string.Empty;

}

protected void Button4_Click(object sender, EventArgs e)

{

if (string.IsNullOrEmpty(TextBox1.Text) || string.IsNullOrEmpty(TextBox2.Text))

{

Label5.Text = "Please Enter Some Values";

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

}

else

{

Label5.Text = "Division Result is: " + (ArthmeticClass.Div(double.Parse(TextBox1.Text), double.Parse(TextBox2.Text)));

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

TextBox1.Text = string.Empty;

TextBox2.Text = string.Empty;

}

Step 7: The output of application looks like this

Step 8: The addition result output of application looks like this