Set hostname - can't write to registry

[WojTec]

I'm trying change host name (like My Computer properties --> Computer Name).

I did this:

Delphi-Quellcode:

if OpenKey('SYSTEM\CurrentControlSet\services\Tcpip\Parameters', True) then
try
  WriteString('NV Hostname', FHostName);
  WriteString('Hostname', FHostName);
finally
  CloseKey;
end;

but raises exception that failed to set data for these values.

So, I tried this:

Delphi-Quellcode:

function SetComputerNameEx(NameType: TComputerNameFormat; lpComputerName: PWideChar): BOOL; stdcall;
  external 'kernel32.dll' name 'SetComputerNameExW';

SetComputerNameEx(ComputerNamePhysicalDnsHostname, 'NewName');

Returns false. I'm administrator.

[DeddyH]

Zitat:

SetComputerNameEx function

...

Return value

If the function succeeds, the return value is a nonzero value.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

What does GetLastError return?

[Bernhard Geyer]

Zitat von WojTec:

Returns false. I'm administrator.

Did you start your application with administration rights (Run as Administrator)?

[WojTec]

I have admin rights.

Last error looks to be success, but SetComputerName and SetComputerNameEx returns false.

[himitsu]

Zitat von WojTec:

I have admin rights.

You might, but also the program?

Zitat:

Last error looks to be success, but SetComputerName and SetComputerNameEx returns false.

And how did you tested it?

[WojTec]

Delphi-Quellcode:

//  ShowMessage(BoolToStr(SetComputerName('TTX'), True));
//  ShowMessage(SysErrorMessage(GetLastError));

  // Set computer name and host name
  ShowMessage(BoolToStr(SetComputerNameEx(ComputerNamePhysicalDnsHostname, 'TTX-N'), True));

  // Set computer name
  ShowMessage(BoolToStr(SetComputerNameEx(ComputerNamePhysicalNetBIOS, 'TTX'), True));

I tried with Run as admin too.
On WXP is working, on W7 is not working.

[himitsu]

Zitat:

Delphi-Quellcode:

ShowMessage(BoolToStr(SetComputerName('TTX'), True));
ShowMessage(SysErrorMessage(GetLastError));

ShowMessage benutzt die WinAPI.
Und nun rate mal, vor welchem API-Aufruf das GetLastError den Status liefert?

Tipp: Das Anzeigen des Message-Form war erfolgreich.

[WojTec]

I don't understand what you mean. What I should to do to make it working?

[jaenicke]

You have to ensure, that no other API function is called after the one you want to check against errors. Otherwise the error state is overwritten before you check it...
But here you call ShowMessage for the result of SetComputerName and fetch the error after this. So you won't get an error unless ShowMessage fails...
What about this way?

Delphi-Quellcode:

if SetComputerName('TTX') then
  ShowMessage('Success')
else
  ShowMessage(SysErrorMessage(GetLastError));

[WojTec]

Hm, now return True, but names are not changed after restart