Create CSV/Excel file in C#

Export GridView data in Excel

Export datatable's data in Excel

Export Data in Excel using Asp.net

using below code you can export data in .csv file which can be opened in excel.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Collections.Generic;
using System.Text;

/// 

/// Summary description for csvexport
/// 
public class CSVExporter
{
    
    public static void WriteToCSV(List personList)
    {
        string attachment = "attachment; filename=PersonList.csv";
        HttpContext.Current.Response.Clear();
        HttpContext.Current.Response.ClearHeaders();
        HttpContext.Current.Response.ClearContent();
        HttpContext.Current.Response.AddHeader("content-disposition", attachment);
        HttpContext.Current.Response.ContentType = "text/csv";
        HttpContext.Current.Response.AddHeader("Pragma", "public");
        WriteColumnName();
        foreach (Person person in personList)
        {
            WriteUserInfo(person);
        }
        HttpContext.Current.Response.End();
    }

    private static void WriteUserInfo(Person person)
    {
        StringBuilder stringBuilder = new StringBuilder();
        AddComma(person.name , stringBuilder);
        AddComma(person.address , stringBuilder);       
        HttpContext.Current.Response.Write(stringBuilder.ToString());
        HttpContext.Current.Response.Write(Environment.NewLine);
    }

    private static void AddComma(string value, StringBuilder stringBuilder)
    {
        stringBuilder.Append(value.Replace(',', ' '));
        stringBuilder.Append(", ");
    }

    private static void WriteColumnName()
    {
        string columnNames = "RegistrationType, Value";
        HttpContext.Current.Response.Write(columnNames);
        HttpContext.Current.Response.Write(Environment.NewLine);
    }
}
public class Person
{
    public string name;
    public string address;
    public Person()
    {

    }
    public Person( string name , string address)
    {
        this.name = name;
        this.address = address;
    }
}

Solution By: Rajesh Rolen