Question

I have this P/Invoke RegSetValueExW that sets the value to the registry key. in C#

[DllImport('coredll.dll', EntryPoint = 'RegSetValueExW')] public static extern int RegSetValueExW(uint hKey, string lpValueName,             uint lpReserved,             uint lpType,             byte[] lpData,             uint lpcbData); 

I’m having a problem with the 4th param byte[] lpdata. I need to pass a DWORD with a value of 5 (int) in it. Everything is OK if I pass a string (REG_SZ), just need to convert using the GetBytes function.

If I call GetBytes(‘5’) it converts it to ascii value of 53 so it writes 53 on the registry value instead of 5

Answer 1

I’ve got to start by asking why you are using PInvoke here when there is already a method for setting registry values in the Microsoft.Win32.RegistryKey class? Or are you stuck using an old version of the Compact Framework?

Assuming you have a good reason for the PInvoke, the easiest answer is just to overload the PInvoke declaration for integer values. i.e.:

[DllImport('coredll.dll', EntryPoint = 'RegSetValueExW')] public static extern int RegSetValueExW(uint hKey, string lpValueName,         uint lpReserved,         uint lpType,         ref int lpData,         uint lpcbData);