Microsoft KB Archive/117261

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PRB: RegCreateKeyEx Gives Error 161 Under Windows NT

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Q117261

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The information in this article applies to:


 * Microsoft Win32 Application Programming Interface (API), used with:
 * the operating system: Microsoft Windows NT, versions 3.5, 3.51, 4.0
 * Microsoft Windows 95
 * the operating system: Microsoft Windows 2000

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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    #include 

#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); } NOTE: Double backslashes ("\\") are required in strings in C code to represent a single backslash, since a backslash ordinarily indicates the beginning of an escape sequence.

Additional query words:

Keywords : kbKernBase kbOSWin2000 kbRegistry kbDSupport kbGrpDSKernBase

Issue type : kbprb

Technology : kbAudDeveloper kbWin32sSearch kbWin32API