DLL in VB 6.0,VB.Net,C#

Hi......

DLL statds for Dynamic Link Library which comprise Business logic .At A huge level of 

Software development it is suitable to implement business login separately. 

DLL provides facility of reversibility means  ones you have been created a DLL 

for a task then many project can use your DLL, Like if you have a DLL of

Calculator logic then many Application can use it after importing DLL ij their project...

DLL in VB 6.0

• Open VB 6.0 and select ActiveXdll
• Change your final project name as you're going to make otherwise you may be face problem of name contradiction because default name of dll project is Project 1 and VB Standard exe has also same so change name of dll project or standard exe project
• On Project explorer window change of class1 as your requirement
• now make some procedure and function of your logic as showing in following picture
• Save DLL project
• For make DLL select File > Make Project1 DLL...
• Now your DLL is ready to use

How to use This DLL

• Open VB 6.0
• Select Standard EXE
• For add a DLL in your project ..
• Go to Project > Refereneces.
• Browse Your DLL File and click open
• Now you can use DLL class
• Make an object of class which you have made in your DLL project
• Call function of your DLL class using . operator

After import DLL you can use it at anywhere here is code which you can use on a button click event

Private Sub Command1_Click()

    Dim ob As New Class1

    ob.Show

    

End Sub

Private Sub Command2_Click()

    Dim ob As New Class1

    MsgBox (ob.Sum(10, 20))

End Sub

DLL in C# and VB.Net

• Open Visual studio 2008 File > Project > Select class library form template
• Implement your function and logic inside class body
• After implementing logic press f6 for build your DLL Project
• For use a DLL in windows Application right click of root folder from solution explorer
• Add References..
• Browse your project DLL
• Now make an object of class which you have named in DLL file

Code of DLL my DLL file

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ClassLibrary1

{

    public class Class1

    {

        public int sum(int a,int b)

        {

            return a + b;

        }

    }

}

Code of window Application file where DLL has been used 

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

namespace WindowsFormsApplication1

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)

        {

            ClassLibrary1.Class1 ob = new ClassLibrary1.Class1();

            MessageBox.Show(ob.sum(10,20).ToString());

        }

    }

}