The CsvExporter class allows exporting data to a csv file, using generic methods and reflection.

CsvExporter.cs

using System;
using System.Collections.Generic;
using System.Data.SqlTypes;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;

namespace Example.Export.CSV
{
    public class CsvExporter : IDisposable
    {
        private List<string> _headers;
        private List<Dictionary<string, object>> _rows;

        public CsvExporter()
        {
            _headers = new List<string>();
            _rows = new List<Dictionary<string, object>>();
        }

        public void AddRow<T>(T element)
        {
            IList<PropertyInfo> properties = typeof(T).GetProperties();

            var headers = properties
                .Select(p => p.Name)
                .Where(h => !_headers.Contains(h));

            _headers.AddRange(headers);

            var row = properties.ToDictionary(
                property => property.Name, 
                property => property.GetValue(element));

            _rows.Add(row);
        }

        public void AddRows<T>(IEnumerable<T> elements)
        {
            foreach (var element in elements)
                AddRow(element);
        }

        private string Encode(object value)
        {
            if (value == null) 
                return string.Empty;

            if (value is INullable && ((INullable)value).IsNull) 
                return string.Empty;

            if (value is DateTime)
            {
                var datetime = (DateTime) value;
                return datetime.ToString("MM/dd/yyyy");
            }

            var result = value.ToString();
            if (result.Contains(",") || result.Contains("\""))
                result = '"' + result.Replace("\"", "\"\"") + '"';

            return result;
        }

        public string Export()
        {
            var sb = new StringBuilder();

            // The headers
            foreach (var header in _headers)
                sb.Append(FormatCamelCase(header))
                  .Append(",");

            sb.AppendLine();

            // The rows
            foreach (var row in _rows)
            {
                foreach (var header in _headers)
                    sb.Append(row.ContainsKey(header) ? Encode(row[header]) : string.Empty)
                      .Append(",");
                sb.AppendLine();
            }

            return sb.ToString();
        }

        public void ExportToFile(string path)
        {
            File.WriteAllText(path, Export());
        }

        public byte[] ExportToBytes()
        {
            return Encoding.UTF8.GetBytes(Export());
        }

        public void Dispose()
        {
            _headers = null;
            _rows = null;
        }

        private string FormatCamelCase(string s)
        {
            var b = new StringBuilder();
            int j = 0;
            for (int i = 0; i < s.Length; i++)
            {
                b.Append(s[i]);
                if (char.IsUpper(s[i]))
                    b.Insert(i + j++, ' ');
            }
            return b.ToString().TrimStart();
        }
    }
}