RegOpenKeyEx info  Overview  Group

The RegOpenKeyEx function opens the specified key.

LONG RegOpenKeyEx(

Parameters

hKey

Identifies a currently open key or any of the following predefined reserved handle values:

HKEY_CLASSES_ROOT
HKEY_CURRENT_CONFIG
HKEY_CURRENT_USER
HKEY_LOCAL_MACHINE
HKEY_USERS
Windows NT only: HKEY_PERFORMANCE_DATA 
Windows 95 only: HKEY_DYN_DATA 

lpSubKey

Points to a null-terminated string containing the name of the subkey to open. If this parameter is NULL or a pointer to an empty string, the function will open a new handle of the key identified by the hKey parameter. In this case, the function will not close the handles previously opened.

ulOptions

Reserved; must be zero.

samDesired

Specifies an access mask that describes the desired security access for the new key. This parameter can be a combination of the following values:

Value	Meaning
KEY_ALL_ACCESS	Combination of KEY_QUERY_VALUE, KEY_ENUMERATE_SUB_KEYS, KEY_NOTIFY, KEY_CREATE_SUB_KEY, KEY_CREATE_LINK, and KEY_SET_VALUE access.
KEY_CREATE_LINK	Permission to create a symbolic link.
KEY_CREATE_SUB_KEY	Permission to create subkeys.
KEY_ENUMERATE_SUB_KEYS	Permission to enumerate subkeys.
KEY_EXECUTE	Permission for read access.
KEY_NOTIFY	Permission for change notification.
KEY_QUERY_VALUE	Permission to query subkey data.
KEY_READ	Combination of KEY_QUERY_VALUE, KEY_ENUMERATE_SUB_KEYS, and KEY_NOTIFY access.
KEY_SET_VALUE	Permission to set subkey data.
KEY_WRITE	Combination of KEY_SET_VALUE and KEY_CREATE_SUB_KEY access.

phkResult

Points to a variable that receives the handle of the opened key.

Return Values

If the function succeeds, the return value is ERROR_SUCCESS.

If the function fails, the return value is a nonzero error code defined in WINERROR.H. You can use the FormatMessage function with the FORMAT_MESSAGE_FROM_SYSTEM flag to get a generic description of the error.

Remarks

Unlike the RegCreateKeyEx function, the RegOpenKeyEx function does not create the specified key if the key does not exist in the registry.

See Also

RegCloseKey, RegCreateKeyEx, RegDeleteKey, RegOpenKey

Jeffrey T Greenberg of BERG Software Says:

the order of the HKEY's is wrong here, it is not critical, but if you don't have the ordinals then it is a bit tougher to figure them out. the order and their ordinals (for XP) is:
HKEY_CLASSES_ROOT = &H80000000
HKEY_CURRENT_USER = &H80000001
HKEY_LOCAL_MACHINE = &H80000002
HKEY_USERS = &H80000003
HKEY_CURRENT_CONFIG = &H80000004

But without what was written above, I would not have gotten the info I needed as fast so I hope I'm not too critical.

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