how to query sql server database size

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data.SqlClient;

using System.Data;

namespace ConsoleApplication2

{

    class Program

    {

        static void Main(string[] args)

        {

            string strCount;

            SqlConnection Conn = new SqlConnection

               ("Data Source=W3INTECH-PC\\sqlexpress;Initial Catalog=aliintDatb;Integrated Security=True;");

            SqlCommand testCMD = new SqlCommand

               ("sp_spaceused", Conn);

            testCMD.CommandType = CommandType.StoredProcedure;

            Conn.Open();

            SqlDataReader reader = testCMD.ExecuteReader();

            if (reader.HasRows)

            {

                while (reader.Read())

                {

                    Console.WriteLine("Name: " + reader["database_name"]);

                    Console.WriteLine("Size: " + reader["database_size"]);

                }

            }

            Console.ReadLine();

        }

    }

}