Question

I’ve run into a strange problem: when setting values of the DWORD type in the Windows Registry from my C# application, I keep getting errors when the highest bit is set. Apparently there seems to be some kind of conversion problem between signed and unsigned integers.

Example: when I do something like this

regKey.SetValue("Value", 0x70000000u, RegistryValueKind.DWord);

it works fine. But when I add the highest bit (which, since I’m specifically dealing with unsigned integers, should be just another value bit), like this

regKey.SetValue("Value", 0xf0000000u, RegistryValueKind.DWord);

I get an exception (“The type of the value object did not match the specified RegistryValueKind or the object could not be properly converted”).

But shouldn’t it work? DWORD is an unsigned 32-bit integer data type, and so is the 0xf0000000u literal (C# automatically assigns it the UInt32 datatype), so they should be a perfect match (and setting the value manually in the registry editor to “0xf0000000” works fine, too). Is this a bug in .NET or am I doing something wrong?

Answer 1

My guess is that you need to use a signed int instead. So just convert it like this:

regKey.SetValue("Value", unchecked((int) 0xf0000000u),
                RegistryValueKind.DWord);

I agree it’s a bit odd, when you consider that DWORD is normally unsigned (IIRC) but it’s at least worth a try…