Registry.DynData Field

Contains dynamic registry data. This field reads the Windows registry base key HKEY_DYN_DATA.

[Visual Basic]
Public Shared ReadOnly DynData As RegistryKey
[C#]
public static readonly RegistryKey DynData;
[C++]
public: static RegistryKey* DynData;
[JScript]
public static var DynData : RegistryKey;

Remarks

The Windows 98/Windows Me registry supports both static data (which is stored on disk in the registry) and dynamic data (which changes frequently, such as performance statistics). This dynamic data area is the mechanism that allows Virtual Device Drivers (VxDs) to provide real-time data to Win32 applications that can run remotely as well as locally. It also allows the system monitor to provide performance statistics on remote Windows 98/Windows Me systems.

VxDs are not limited to performance data. They can provide any data they want to pass from Ring 0 to Ring 3 efficiently without monopolizing the CPU. The registry supports dynamic data by storing a pointer to a function that returns a value (or many values). When a Registry call queries values associated with a dynamic key, that function is called to return the desired value or values.

Note   Dynamic keys were introduced in Microsoft Windows 95 to handle dynamic Registry data. They are supported only in Windows 98/Windows Me.

Example

[Visual Basic, C#, C++] The following example demonstrates how to retrieve the subkeys of this key, and prints their names to the screen. Use the OpenSubKey method to create an instance of the particular subkey of interest. You can then use other operations in RegistryKey to manipulate that key. Note that this example can return no results, since there might not be dynamic data available, or you might not be running Windows 98/ME. Using this key may cause an error on other systems.

[Visual Basic] 
Imports System
Imports Microsoft.Win32

Class Reg
    
    Public Shared Sub Main()
        
        ' Create a RegistryKey, which will access the HKEY_DYN_DATA
        ' key in the registry of this machine.
        Dim rk As RegistryKey = Registry.DynData
        
        ' Print out the keys.
        PrintKeys(rk)
    End Sub    
    
    Shared Sub PrintKeys(rkey As RegistryKey)
        
        ' Retrieve all the subkeys for the specified key.
        Dim names As String()
        Try
            names = rkey.GetSubKeyNames()
        Catch ex As System.IO.IOException
            Console.WriteLine("HKEY_DYN_DATA is not available on this machine.")
            Exit Sub
        End Try
        
        Dim icount As Integer = 0
        
        Console.WriteLine("Subkeys of " & rkey.Name)
        Console.WriteLine("-----------------------------------------------")
        
        ' Print the contents of the array to the console.
        Dim s As String
        For Each s In  names
            Console.WriteLine(s)
            
            ' The following code puts a limit on the number
            ' of keys displayed.  Comment it out to print the
            ' complete list.
            icount += 1            
            If icount >= 10 Then
                Exit For
            End If
        Next s
    End Sub
End Class

[C#] 
using System;
using Microsoft.Win32;

class Reg {
    public static void Main() {

        // Create a RegistryKey, which will access the HKEY_DYN_DATA
        // key in the registry of this machine.
        RegistryKey rk = Registry.DynData;

        // Print out the keys.
        PrintKeys(rk);
    }

    static void PrintKeys(RegistryKey rkey) {

        // Retrieve all the subkeys for the specified key.
        String [] names;
        try {
            names = rkey.GetSubKeyNames();
        }
        catch (System.IO.IOException e) {
            Console.WriteLine("HKEY_DYN_DATA is not available on this machine.");
            return;
        }

        int icount = 0;

        Console.WriteLine("Subkeys of " + rkey.Name);
        Console.WriteLine("-----------------------------------------------");

        // Print the contents of the array to the console.
        foreach (String s in names) {
            Console.WriteLine(s);

            // The following code puts a limit on the number
            // of keys displayed.  Comment it out to print the
            // complete list.
            icount++;
            if (icount >= 10)
                break;
        }
    }
}

[C++] 
#using <mscorlib.dll>
using namespace System;
using namespace Microsoft::Win32;

void PrintKeys(RegistryKey* rkey) {

    // Retrieve all the subkeys for the specified key.
    String* names[];
    try {
        names = rkey->GetSubKeyNames();
    }
    catch (System::IO::IOException*) {
        Console::WriteLine(S"HKEY_DYN_DATA is not available on this machine.");
        return;
    }

    int icount = 0;

    Console::WriteLine(S"Subkeys of {0}", rkey->Name);
    Console::WriteLine(S"-----------------------------------------------");

    // Print the contents of the array to the console.
    System::Collections::IEnumerator* enum0 = names->GetEnumerator();
    while (enum0->MoveNext())
    {
        String* s = __try_cast<String*>(enum0->Current);
        Console::WriteLine(s);

        // The following code puts a limit on the number
        // of keys displayed.  Comment it out to print the
        // complete list.
        icount++;
        if (icount >= 10)
            break;
    }
}

int main() {

    // Create a RegistryKey, which will access the HKEY_DYN_DATA
    // key in the registry of this machine.
    RegistryKey* rk = Registry::DynData;

    // Print out the keys.
    PrintKeys(rk);
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

Registry Class | Registry Members | Microsoft.Win32 Namespace