Reading from and Writing to the Registry Using the Microsoft.Win32 Namespace (Visual Basic)
Keys in the Registry Class
The Registry class supplies the base registry keys that can be used to access subkeys and their values. The base keys themselves are read-only. The following table lists and describes the seven keys exposed by the Registry class.
|ClassesRoot||Defines the types of documents and the properties associated with those types.|
|CurrentConfig||Contains hardware configuration information that is not user-specific.|
|CurrentUser||Contains information about the current user preferences, such as environmental variables.|
|DynData||Contains dynamic registry data, such as that used by Virtual Device Drivers.|
|LocalMachine||Contains five subkeys (Hardware, SAM, Security, Software, and System) that hold the configuration data for the local computer.|
|PerformanceData||Contains performance information for software components.|
|Users||Contains information about the default user preferences.|
It is more secure to write data to the current user (CurrentUser) than to the local computer (LocalMachine). A condition that's typically referred to as "squatting" occurs when the key you are creating was previously created by another, possibly malicious, process. To prevent this from occurring, use a method, such as GetValue, that returns
Nothing if the key does not already exist.
Reading a Value from the Registry
The following code shows how to read a string from HKEY_CURRENT_USER.
Dim regVersion As Microsoft.Win32.RegistryKey Dim keyValue = "Software\\Microsoft\\TestApp\\1.0" regVersion = Microsoft.Win32.Registry.CurrentUser.OpenSubKey(keyValue, False) Dim intVersion As Integer = 0 If regVersion IsNot Nothing Then intVersion = regVersion.GetValue("Version", 0) regVersion.Close() End If
The following code reads, increments, and then writes a string to HKEY_CURRENT_USER.
Dim regVersion = Microsoft.Win32.Registry.CurrentUser.OpenSubKey( "SOFTWARE\\Microsoft\\TestApp\\1.0", True) If regVersion Is Nothing Then ' Key doesn't exist; create it. regVersion = Microsoft.Win32.Registry.CurrentUser.CreateSubKey( "SOFTWARE\\Microsoft\\TestApp\\1.0") End If Dim intVersion As Integer = 0 If regVersion IsNot Nothing Then intVersion = regVersion.GetValue("Version", 0) intVersion = intVersion + 1 regVersion.SetValue("Version", intVersion) regVersion.Close() End If