C# generic extension method to convert a list of type to a CSV string.

public static string ToCsv<T>(this List<T> list)
{
    StringBuilder sb = new StringBuilder();

    //Get the properties for type T for the headers
    PropertyInfo[] propInfos = typeof(T).GetProperties();
    for (int i = 0; i <= propInfos.Length - 1; i++)
    {
        sb.Append(propInfos[i].Name);

        if (i < propInfos.Length - 1)
        {
            sb.Append(",");
        }
    }

    sb.AppendLine();

    //Loop through the collection, then the properties and add the values
    for (int i = 0; i <= list.Count - 1; i++)
    {
        T item = list[i];
        for (int j = 0; j <= propInfos.Length - 1; j++)
        {
            object o = item.GetType().GetProperty(propInfos[j].Name).GetValue(item, null);
            if (o != null)
            {
                string value = o.ToString();

                //Check if the value contans a comma and place it in quotes if so
                if (value.Contains(","))
                {
                    value = string.Concat("\"", value, "\"");
                }

                //Replace any \r or \n special characters from a new line with a space
                if (value.Contains("\r"))
                {
                    value = value.Replace("\r", " ");
                }
                if (value.Contains("\n"))
                {
                    value = value.Replace("\n", " ");
                }

                sb.Append(value);
            }

            if (j < propInfos.Length - 1)
            {
                sb.Append(",");
            }
        }

        sb.AppendLine();
    }

    return sb.ToString();
}