Reading and Writing Registry in .NET

If you have ever read/write registry using Win APIs RegOpenKeyEx, RegCreateKeyEx, and RegCloseKey, you must be familiar with the complexity of these APIs. In .NET framework, the Registry and the RegistryKey classes provide control to the Windows Registry. These classes are easy to use. 

These classes are defined in Microsoft.Win32 namespace and mscorlib.dll assembly. You need to use the namespace and the assembly before use these classes.  

#using <mscorlib.dll>
using namespace Microsoft::Win32;

The Registry class only have seven field members which gives you access to particular area of the registry. It's similar to opening a key in the registry. These all members return a pointer to RegistryKey.

ClassesRoot : The Windows Registry base key HKEY_CLASSES_ROOT.
CurrentConfig : The Windows Registry base key HKEY_CURRENT_CONFIG.
CurrentUser : The Windows Registry base key HKEY_CURRENT_USER.
DynData : The Windows Registry base key HKEY_DYN_DATA.
LocalMachine : The Windows Registry base key HKEY_LOCAL_MACHINE.
PerformanceData : The Windows Registry base key HKEY_PERFORMANCE_DATA.
Users : The Windows Registry base key HKEY_USERS.

Say you want to read/write data of HKEY_LOCAL_MACHINE. 

RegistryKey* pRegKey = Registry::LocalMachine;  

Now you call OpenSubKey of RegistryKey to open a key and GetValue to get the value of a string.

pRegKey->OpenSubKey(L"SOFTWARE\\Kruse Inc\\Version");
Object *pValue = pRegKey->GetValue(L"kWise");

The SetValue member of this class is used to write a value for a registry key.

pRegKey->SetValue(L"kWise", "some Value Here");

You use DeleteValue to delete a value.

pRegKey->DeleteValue(L"kWise");

Other members:

DeleteSubKey : Deletes a subkey
CreateSubKey : Opens a subkey if key is already exists. Creates new otherwise.
DeleteSubKeyTree : Deletes subkey and its nodes  

Sample Example:

#using <mscorlib.dll>
using namespace System;
using namespace Microsoft::Win32;

int main(void)
{
RegistryKey * pRegKey = Registry::LocalMachine;
pRegKey = pRegKey->OpenSubKey(L"HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0");
Object *pValue = pRegKey->GetValue(L"VendorIdentifier");
Console::WriteLine(L"The central processor of this machine is: {0}.", pValue);
return 0;
}