PRB: RegCreateKeyEx() Gives Error 161 Under Windows NT

• Microsoft Win32 Application Programming Interface (API) included with: - Microsoft Windows NT version 3.5, 3.51, 4.0 - Microsoft Windows 95

SYMPTOMS

A call to RegCreateKeyEx() is successful under Windows NT version 3.1 and Windows 95, but the call fails with error 161 (ERROR_BAD_PATHNAME) under Windows NT version 3.5 and later.

The sample code below demonstrates this problem.

CAUSE

This is by design. Windows NT version 3.1 and Windows 95 allow the subkey to begin with a backslash ("\"), however Windows NT version 3.5 and later do not. The subkey is given as the second parameter to RegCreateKeyEx().

RESOLUTION

Remove the backslash from the beginning of the subkey name.

MORE INFORMATION

In the sample code below, RegCreateKeyEx() fails with error 161 while the string defined by SUBKEY_FORMAT_STRING begins with a backslash, but succeeds if the initial backslash is removed.

Sample Code

   #include <windows.h>
   #include <stdio.h>

   #define SUBKEY_FORMAT_STRING \
   "\\SYSTEM\\CurrentControlSet\\Services\\EventLog\\Application\\%s"

   void main(int argc, char *argv[])
   {
      DWORD dwErrorCode;
      char lpszSubKey[MAX_PATH];
      HKEY hKey;
      DWORD dwDisposition;

      sprintf( lpszSubKey, SUBKEY_FORMAT_STRING, argv[1] );

      printf( "Trying to open: %s\n", lpszSubKey );

      dwErrorCode = RegCreateKeyEx(HKEY_LOCAL_MACHINE,
                                   lpszSubKey,
                                   0,
                                   "",
                                   REG_OPTION_NON_VOLATILE,
                                   KEY_ALL_ACCESS,
                                   NULL, //Security
                                   &hKey,
                                   &dwDisposition );

      if (dwErrorCode != ERROR_SUCCESS)
         printf( "Code = %d.\n", dwErrorCode );

      RegCloseKey(hKey);
   }