csharp: read system DSN configured get Driver Names on windows

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using Microsoft.Win32;
using System.Data.Odbc;

namespace SQLanyWhereDemo
{
    public partial class Form5 : Form
    {

        [DllImport("odbc32")]
        public static extern short SQLAllocHandle(short HandleType, IntPtr InputHandle, out IntPtr OutputHandle);
        [DllImport("odbc32", CharSet = CharSet.Unicode)]
        public static extern short SQLSetEnvAttr(IntPtr envHandle, ushort attribute, IntPtr val, int stringLength);
        [DllImport("odbc32.dll", CharSet = CharSet.Ansi)]
        public static extern short SQLDataSources(IntPtr EnvironmentHandle, ushort Direction, StringBuilder ServerName, short BufferLength1, ref short NameLength1Ptr, StringBuilder Description, short BufferLength2, ref short NameLength2Ptr);
        [DllImport("ODBCCP32.dll")]
        private static extern bool SQLConfigDataSource(IntPtr parent, int request, string driver, string attributes);

        [DllImport("odbccp32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
        private static extern bool SQLGetInstalledDriversW(char[] lpszBuf, ushort cbufMax, out ushort pcbBufOut);

        public const int SQL_SUCCESS = 0;
        public const int SQL_ERROR = -1;

        public const int SQL_FETCH_NEXT = 1;
        public const int SQL_FETCH_FIRST = 2;
        public const int SQL_FETCH_FIRST_USER = 31;
        public const int SQL_FETCH_FIRST_SYSTEM = 32;

        public const int SQL_ATTR_ODBC_VERSION = 200;

        public const int SQL_HANDLE_ENV = 1;
        public const int SQL_HANDLE_DBC = 2;
        public const int SQL_HANDLE_STMT = 3;
        public const int SQL_HANDLE_DESC = 4;
        /// <summary>
        /// 
        /// </summary>
        public Form5()
        {
            InitializeComponent();
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button1_Click(object sender, EventArgs e)
        {

            List<ODBCStr> ls = new List<ODBCStr>();
            short iResult = 0;
            IntPtr lhEnvIn = (IntPtr)0;
            IntPtr lhEnv = (IntPtr)0;
            StringBuilder sDSNItem = new StringBuilder(1024);
            StringBuilder sDRVItem = new StringBuilder(1024);
            short iDSNLen = 0;
            short iDRVLen = 0;

            SQLSetEnvAttr(lhEnv, 200, (IntPtr)3, 0);

            iResult = SQLAllocHandle(1, lhEnvIn, out lhEnv);
            MessageBox.Show(iResult.ToString(), "iResult SQLAllocHandle");

            //short iResult = 0;
            //IntPtr lhEnvIn = (IntPtr)0;
            //IntPtr lhEnv = (IntPtr)0;
            //StringBuilder sDSNItem = new StringBuilder(1024);
            //StringBuilder sDRVItem = new StringBuilder(1024);
            //short iDSNLen = 0;
            //short iDRVLen = 0;

            iResult = SQLAllocHandle(SQL_HANDLE_ENV, lhEnvIn, out lhEnv);

            SQLSetEnvAttr(lhEnv, SQL_ATTR_ODBC_VERSION, (IntPtr)3, 0);

            if (iResult == SQL_SUCCESS)
            {
                ODBCStr sr = null;
                iResult = SQLDataSources(lhEnv, SQL_FETCH_FIRST, sDSNItem, 1024, ref iDSNLen, sDRVItem, 1024, ref iDRVLen);
                while (iResult == SQL_SUCCESS)
                {
                    sr=new ODBCStr();
                    //MessageBox.Show(sDSNItem.ToString(), "sDSNItem.ToString()");
                    iResult = SQLDataSources(lhEnv, SQL_FETCH_NEXT, sDSNItem, 1024, ref iDSNLen, sDRVItem, 1024, ref iDRVLen);
                    sr.DsnName = sDSNItem.ToString();
                    sr.DriveName = sDRVItem.ToString();
                    //string str = "SERVER=HOMEDSN=MYDSNDESCRIPTION=MYDSNDESCDATABASE=DBServerTRUSTED_CONNECTION=YES";
                    //SQLConfigDataSource((IntPtr)0, 4, "Sybase SQL Anywhere 5.0", str);//SQL Server
                    //MessageBox.Show(str);

                    ls.Add(sr);
                }
            }

            this.dataGridView1.DataSource = ls;

        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button2_Click(object sender, EventArgs e)
        {

            string[] list = GetOdbcDriverNames();


        }

        /// <summary>
        /// Gets the ODBC driver names from the SQLGetInstalledDrivers function.
        /// </summary>
        /// <returns>a string array containing the ODBC driver names, if the call to SQLGetInstalledDrivers was successfull; null, otherwise.</returns>
        public static string[] GetOdbcDriverNames()
        {
            string[] odbcDriverNames = null;
            char[] driverNamesBuffer = new char[ushort.MaxValue];
            ushort size;

            bool succeeded = SQLGetInstalledDriversW(driverNamesBuffer, ushort.MaxValue, out size);

            if (succeeded == true)
            {
                char[] driverNames = new char[size - 1];
                Array.Copy(driverNamesBuffer, driverNames, size - 1);
                odbcDriverNames = (new string(driverNames)).Split('');
            }

            return odbcDriverNames;
        }
    }


    /// <summary>
    /// 涂聚文
    /// 20180223
    /// Geovin Du
    /// </summary>
    public class ODBCStr
    {
        /// <summary>
        /// 
        /// </summary>
        public string DriveName { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string DsnName { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string ServerName { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string DatabaseName { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string DataSrource { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public string DataFile { get; set; }


    }


}

　　

  /// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button3_Click(object sender, EventArgs e)
        {

            //string connectionString = "dsn=LocalServer";
            //System.Data.Common.DbConnectionStringBuilder builder = new System.Data.Common.DbConnectionStringBuilder(); 
            //builder.ConnectionString = connectionString;
            //string server = builder["Data Source"] as string;
            //string database = builder["Initial Catalog"] as string;

            //string conString = "SERVER=localhost;DATABASE=tree;UID=root;PASSWORD=branch;Min Pool Size = 0;Max Pool Size=200";
            //SqlConnectionStringBuilder builder = new SqlConnectionStringBuilder(conString);
            //string user = builder.UserID;
            //string pass = builder.Password;

            //OdbcConnectionStringBuilder buil =new OdbcConnectionStringBuilder();
            //buil.Driver = "Sybase SQL Anywhere 5.0";
            //buil.Dsn = "achive";

            System.Data.Odbc.OdbcConnectionStringBuilder connBuilder = new System.Data.Odbc.OdbcConnectionStringBuilder();
            connBuilder.Dsn = "achive";
            connBuilder.Driver = "Sybase SQL Anywhere 5.0";           
            //connBuilder.Add("uid", "");
            //connBuilder.Add("pwd", "");

            connBuilder.Add("database", "涂聚文");
            
            string sss = connBuilder.ToString();
            //MessageBox.Show(connBuilder.ToString());
            System.Data.Odbc.OdbcConnection conn = new System.Data.Odbc.OdbcConnection(connBuilder.ToString());
            try
            {
                conn.Open();
                System.Data.Odbc.OdbcCommand comm = new System.Data.Odbc.OdbcCommand("select count(*) from item_description", conn);
                var reader = comm.ExecuteReader();
                while (reader.Read())
                {
                    MessageBox.Show(reader[0].ToString());
                }
                MessageBox.Show("连接成功！");
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message.ToString());
            }
            finally
            {
                conn.Close();
            }
          
            //设置
            //OdbcConnectionStringBuilder.Dsn=connectionString;


        }


        /// <summary>
        /// 
        /// </summary>
        /// <param name="Database"></param>
        /// <param name="Version"></param>
        /// <returns></returns>
        public static string GetODBCDriverName(string Database, string Version)
        {

            string ODBCDriverName = "";

            RegistryKey registryKey = Registry.LocalMachine;

            RegistryKey registrySubKey = registryKey.OpenSubKey(@"SOFTWAREODBCODBCINST.INI");

            String[] SubKeyNames = registrySubKey.GetSubKeyNames();

            foreach (String KeyName in SubKeyNames)
            {

                if (KeyName.Contains(Database) && KeyName.Contains(Version))
                {

                    ODBCDriverName = KeyName;

                    break;

                }
            }

            registrySubKey.Close();

            registryKey.Close();

            return ODBCDriverName;

        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button4_Click(object sender, EventArgs e)
        {
                OdbcConnectionStringBuilder odbcConnectionStringBuilder = new OdbcConnectionStringBuilder();
                OdbcCommand odbcCommand;
                int RecordFound = 0;
                odbcConnectionStringBuilder.Driver = GetODBCDriverName("Sybase SQL Anywhere", "5.0");
                if (odbcConnectionStringBuilder.Driver == "")
                {

                    MessageBox.Show(" ODBC Driver is not installed");
                    //return -1;
                }
                odbcConnectionStringBuilder.Add("DSN", "achive");
                //odbcConnectionStringBuilder.Add("UID", "no-user");
                //odbcConnectionStringBuilder.Add("PWD", "no-pass");
                odbcConnectionStringBuilder.Add("DB", @"C:Documents and SettingsgeovinduMy DocumentsVisual Studio 2010ProjectsSQLanyWhereDemoSQLanyWhereDemoinDebuggeovindu.db;"); // copy of database SPORTS
                odbcConnectionStringBuilder.Add("HOST", ".");
                //odbcConnectionStringBuilder.Add("PORT", "5162"); // i found this port inn the log file
                using (OdbcConnection connection = new OdbcConnection(odbcConnectionStringBuilder.ConnectionString))

                {

                    connection.Open();
                        try
                        {
                                odbcCommand = new OdbcCommand("SELECT COUNT(*) FROM pub.Invoice WHERE Invoicenum > 0", connection);
                                odbcCommand.CommandTimeout = 1;
                                object executeScalarResult = odbcCommand.ExecuteScalar();
                                RecordFound = Convert.ToInt32(executeScalarResult);
                        }
                        catch (Exception ex)
                        {
                            MessageBox.Show(ex.Message.ToString());
                        }
               }


    }