C#

public static readonly UIntPtr HKEY_LOCAL_MACHINE = new UIntPtr(0x80000002u);
        public const string lpSubKey = "SECURITY\\Policy\\PolEdtEv";
        public const int KEY_READ = 0x20019;
        public const uint REG_NONE = 0x00000001;
        public const string valueName = "";

        [DllImport("advapi32.dll", EntryPoint = "RegOpenKeyEx")]
        public static extern int RegOpenKeyEx(UIntPtr hKey, string lpSubKey, int ulOptions, int samDesired, out UIntPtr phkResult);

        [DllImport("advapi32.dll", EntryPoint = "RegQueryValueEx")]
        public static extern int RegQueryValueEx(UIntPtr hKey, string pSubKey, int reserved, out uint lpType, IntPtr lpData, ref int lpcbData);

        private static int ReadRegKey(UIntPtr HKEY_LOCAL_MACHINE, string lpSubKey, string valueName)
        {
            UIntPtr hKey;
            //int keyValue = 0;
            // final parameter is the returned key from RegOpen

            if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, lpSubKey, 0, KEY_READ, out hKey) == 0)
            {
                int size = 1024;
                uint type = 0;
                // I could not get StringBuffer to work here
                IntPtr [] keyBuffer = new IntPtr [1024];

                if (RegQueryValueEx(hKey, valueName, 0, out type, keyBuffer, ref size) == 0)
                {
                    int keyValue = keyBuffer;
                    Console.WriteLine(keyBuffer);

                    return keyValue;
                }
            }
            
        }

private static byte[] ReadRegKey(UIntPtr HKEY_LOCAL_MACHINE, string lpSubKey, string valueName)
{
    UIntPtr hKey;
    byte[] keyValue = null;
    // final parameter is the returned key from RegOpen
    
    if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, lpSubKey, 0, KEY_READ, out hKey) == 0)
    {
        Console.WriteLine(valueName);
 
        int size = 1024;
        uint type = 0;
        // this array will be filled by RegQueryValueEx()
        byte[] keyBuffer = new byte[1024];
 
        if (RegQueryValueEx(hKey, valueName, 0, out type, keyBuffer, ref size) == 0)
            keyValue = keyBuffer;
// cannot siplay a byte array - it is not text
//        Console.WriteLine(keyValue);
    }
    return keyValue;
}

static void Main(string[] args)
{
    byte[] regkey = ReadRegKey(HKEY_LOCAL_MACHINE, lpSubKey, "");
    // on return regkey should contain the value obtained from the registry
}

CCodeNewbie wrote:

I knew that Main had to go somewhere

CCodeNewbie wrote:

to go from Beginner to Novice ...

CCodeNewbie wrote:

I have yet to see one on getting "Default" i.e. "unknown" types and REG_NONE values (where the example actually works and some attention seeker isn't just posting garbage)

CCodeNewbie wrote:

thanks muchly to you and Luc.

[DllImport("advapi32.dll",EntryPoint = "RegQueryValueEx")]
        public static extern int RegQueryValueEx(UIntPtr hKey,stringlpValueName,int lpReserved,out uint lpType, IntPtr lpData,ref int lpcbData);

private static int ReadRegKey(UIntPtr HKEY_LOCAL_MACHINE, string lpSubKey, string valueName)
{
   LONG regReturnType = RegOpenKeyEx(HKEY_LOCAL_MACHINE, lpSubKey, 0, KEY_READ, out valueName );

   // Use ERROR_SUCCESS instead of number. I think I have read
   // documentation saying the number may change. Use ERROR_SUCCESS
   // is a sure way.
   if (regReturnType == ERROR_SUCCESS)
   {
           Console.WriteLine(valueName);
 
           int size = 1024;
           uint type;
           string keyValue = String.Empty; // Use String.Empty
           StringBuilder keyBuffer = new StringBuilder();
                
           regReturnType = RegQueryValueEx(HKEY_LOCAL_MACHINE, valueName, 0, out type, keyBuffer, ref size) 
           if (regReturnType == ERROR_SUCCESS)
           {
              keyValue = keyBuffer.ToString();
 
              Console.WriteLine(keyValue);
              // return (keyValue);
              // Passing keyValue outside the function using return
              // is wrong. If you use return, the value you capture
              // for keyValue will never get a value.
           }
           return regReturnType;
   }
   return regReturnType;      
}

Quote:

a) I cannot find the registry value you mentioned in my Win7. Are you sure the value exist somewhere? Is it in Windows server?

Quote:

b) You are not familiar with how function gets parameter from outside and how to pass parameter back to the outside world.

Quote:

please note it is supposed to return an integer

using (OleDbDataReader reader = command.ExecuteReader())
{
    while (reader.Read())
    {
        string foo = reader[0].ToString();
        string newcolumn = foo.Substring(foo.IndexOf(":") + 1);
                            
        object[] meta = new object[reader.FieldCount];
        reader.GetValues(meta);
        List<string> list = meta.ToList().ConvertAll(o => o.ToString());
    }
}