Import/Export data from/to Excel using ASP.NET

Step 1: (Designing)

Default.aspx

1)Set dropdownlist property of Age(AppendDataBoundItems->true and AutoPostBack->true)

2) Set textbox4 Property(TextMode-> MultiLine) .

Note: Display Age values from  1 to 100 using dropdownlist

 DropDownList1.DataSource = Enumerable.Range(1, 100);

 DropDownList1.DataBind();

Step 2: Add coding  

Default.aspx.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using System.IO;

namespace Project

{

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

    {

        protected void Page_Load(object sender, EventArgs e)

        {

            DropDownList1.DataSource = Enumerable.Range(1, 100);

            DropDownList1.DataBind();

        }

        protected void Button1_Click(object sender, EventArgs e)

        {

          

             string path = @"C:\Users\iiht\output.csv";

             string delimiter = ",";

            if(!File.Exists(path))

            {

               string createText = "Column 1 Name" + delimiter + "Column 2 Name" + delimiter + "Column 3 Name" + delimiter +"column 4 Name"+ Environment.NewLine;

                File.WriteAllText(path, createText);

            }

            // This text is always added, making the file longer over time

            // if it is not deleted.

            string appendText = TextBox1.Text + delimiter + TextBox2.Text+ delimiter + TextBox3.Text + delimiter + DropDownList1.SelectedValue + Environment.NewLine;

            File.AppendAllText(path, appendText);

            // Open the file to read from.

            string readText = File.ReadAllText(path);

            Console.WriteLine(readText);

            TextBox1.Text = "";

            TextBox2.Text = "";

            TextBox3.Text = "";

        

        }

        protected void Button2_Click(object sender, EventArgs e)

        {

            string path = @"C:\Users\iiht\output.csv";

            string delimiter = ",";

            string appendText = TextBox1.Text + delimiter + TextBox2.Text + delimiter + TextBox3.Text + delimiter + DropDownList1.SelectedItem.Value + Environment.NewLine ;

            File.AppendAllText(path, appendText);

            // Open the file to read from.

            string readText = File.ReadAllText(path);

           

            TextBox4.Text = readText;

           

        }

    }

}

    Step 3: Run the application

Step 4:

Step 5: