RegCreateKeyEx

The RegCreateKeyEx function creates the specified key. If the key already exists in the registry, the function opens it.

LONG RegCreateKeyEx(

HKEY hKey,	// handle of an open key
LPCTSTR lpSubKey,	// address of subkey name
DWORD Reserved,	// reserved
LPTSTR lpClass,	// address of class string
DWORD dwOptions,	// special options flag
REGSAM samDesired,	// desired security access
LPSECURITY_ATTRIBUTES lpSecurityAttributes,	// address of key security structure
PHKEY phkResult,	// address of buffer for opened handle
LPDWORD lpdwDisposition	// address of disposition value buffer
);

Parameters

hKey

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

HKEY_CLASSES_ROOT
HKEY_CURRENT_USER
HKEY_LOCAL_MACHINE
HKEY_USERS

The key opened or created by the RegCreateKeyEx function is a subkey of the key identified by the hKey parameter.

lpSubKey

Points to a null-terminated string specifying the name of a subkey that this function opens or creates. The subkey specified must be a subkey of the key identified by the hKey parameter. This subkey must not begin with the backslash character ('\'). This parameter cannot be NULL.

Reserved

Reserved; must be zero.

lpClass

Points to a null-terminated string that specifies the class (object type) of this key. This parameter is ignored if the key already exists.

dwOptions

Specifies special options for the key. This parameter can be one of the following values.

Value	Meaning
REG_OPTION_NON_VOLATILE	This key is not volatile; this is the default. The information is stored in a file and is preserved when the system is restarted. The RegSaveKey function saves keys that are not volatile.
REG_OPTION_VOLATILE	Windows NT: This key is volatile; the information is stored in memory and is not preserved when the system is restarted. The RegSaveKey function does not save volatile keys. This flag is ignored if the key already exists. Windows 95: This value is ignored in Windows 95. If REG_OPTION_VOLATILE is specified, the RegCreateKeyEx function creates a nonvolatile key and returns ERROR_SUCCESS.
REG_OPTION_BACKUP_RESTORE	Windows NT: If this flag is set, the function ignores the samDesired parameter and attempts to open the key with the access required to backup or restore the key. If the calling thread has the SE_BACKUP_NAME privilege enabled, the key is opened with ACCESS_SYSTEM_SECURITY and KEY_READ access. If the calling thread has the SE_RESTORE_NAME privilege enabled, the key is opened with ACCESS_SYSTEM_SECURITY and KEY_WRITE access. If both privileges are enabled, the key has the combined accesses for both privileges. Windows 95: This flag is ignored. Windows 95 does not support security in its registry.

samDesired

Specifies an access mask that specifies 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.

lpSecurityAttributes

Pointer to a SECURITY_ATTRIBUTES structure that determines whether the returned handle can be inherited by child processes. If lpSecurityAttributes is NULL, the handle cannot be inherited.

Windows NT: The lpSecurityDescriptor member of the structure specifies a security descriptor for the new key. If lpSecurityAttributes is NULL, the key gets a default security descriptor.

Windows 95: The lpSecurityDescriptor member of the structure is ignored.

phkResult

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

lpdwDisposition

Points to a variable that receives one of the following disposition values:

Value	Meaning
REG_CREATED_NEW_KEY	The key did not exist and was created.
REG_OPENED_EXISTING_KEY	The key existed and was simply opened without being changed.

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

The key that the RegCreateKeyEx function creates has no values. An application can use the RegSetValue or RegSetValueEx function to set key values.

The key identified by the hKey parameter must have been opened with KEY_CREATE_SUB_KEY access. To open the key, use the RegCreateKeyEx or RegOpenKeyEx function.

An application cannot create a key under HKEY_USERS or HKEY_LOCAL_MACHINE.

An application can use RegCreateKeyEx to temporarily lock a portion of the registry. When the locking process creates a new key, it receives the disposition value REG_CREATED_NEW_KEY, indicating that it "owns" the lock. Another process attempting to create the same key receives the disposition value REG_OPENED_EXISTING_KEY, indicating that another process already owns the lock.

See Also

RegCloseKey, RegCreateKey, RegDeleteKey, RegOpenKey, RegOpenKeyEx, RegSaveKey, SECURITY_ATTRIBUTES

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