How can Create DLL File and Use it in .NET Application

If there is some reusable code ,which has to be used in more than one application,instead of specify the same code again and again,we can make a DLL File. DLL can not be execute independently.

There are some steps to make a .dll file and use it in .Net Application.Please follow steps one by one which are given below.

Step1:- First open your visual studio->go File->New Project->Select class Library->Click OK.

see it:-

Step2:- First open solution Explorer->Right click on  dll exampe->Add Reference->click on .NET->Select System.Windows.Forms->click OK.

Step3:- Write the following code which are given below:-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace dllexample
{
    public class Class1
    {
        public void sum(int i, int ii)
        {
            int res = i + ii;

            MessageBox.Show(res.ToString());
        }

        public void multi(int i, int ii)
        {
            int res = i *ii;
            MessageBox.Show(res.ToString());
        }

    }
}

Step:4- Compile the program (Press F6).

Step5:- Now again open New Project->Select WindowsFormsApplication-> Click OK->Make the design which is as shown below:-

Step6:- Open Solution Explorer->Right click on solution Explorer->Click Add Reference->select Browse->Go dllexample File->Bin->Debug->select dlleample->OK.

Step7:-   Double click on Getsum and Getmultiple button and write the following which are given below.

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)
        {
            dllexample.Class1 obj = new dllexample.Class1();
           int a=Convert.ToInt32(textBox1.Text);
            int b=Convert.ToInt32(textBox2.Text);
        obj.sum(a,b);
            
        }

        private void button2_Click(object sender, EventArgs e)
        {

            dllexample.Class1 obj = new dllexample.Class1();
            int a= Convert.ToInt32(textBox3.Text);
            int b = Convert.ToInt32(textBox4.Text);
            obj.multi(a,b);
        }
    }
}

see it:

Step7:- Now Run the program (press F5) ,the output of program is shown below :-
see it:-

.
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I hope this is helpful for you.

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