using System;

using System.Data;

using System.Xml;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        DataTable d = new DataTable();

        d.Columns.Add("col1", typeof(string));

        d.Columns.Add("col2", typeof(string));

        d.Columns.Add("col3", typeof(string));

        d.Rows.Add("val1", "val2", "val3");

        string json = JsonConvert.SerializeObject(d);

        Console.WriteLine(json);

    }

}