API function for registry operations (regopenkeyex: used to open a specific registry key)

Regopenkeyex: This function is used to open a specific registry key. The registry key value is case-insensitive.

This remote call interface also exists, and the function name is ceregopenkeyex
Long regopenkeyex (
Hkey,
Lpwstr lpsubkey,
DWORD uloptions,
Regsam samdesired,
Phkey phkresult
);
Parameters
Parameters
Hkey
Input parameter to identify the currentRegcreatekeyexOr the registry key handle opened by regopenkeyex, or the following pre-defined handle
Hkey_classes_root
HKEY_CURRENT_USER
HKEY_LOCAL_MACHINE
HKEY_USERS

Lpsubkey
Input parameter, which points to a string used to save the name of the Registry to be opened. If this parameter is null or a pointer to an empty string, the function opens a key defined by the hkey. In this case, this function does not close the handle opened by the port wall.
Uloptions
Input parameter, reserved, set to 0

Samdesired
Input parameter. Indicates the permission to open the Registry. If the security descriptor of this parameter does not allow the current process to access the registry, the function returns a failure. For detailed security descriptions, see the following table:

Key_all_access (0xf003f)	Combines the standard_rights_required, key_query_value, key_set_value, key_create_sub_key, key_enumerate_sub_keys, key_policy, and key_create_link access rights.
Key_create_link (0x0020)	Reserved for system use.
Key_create_sub_key (0x0004)	Required to create a subkey of a registry key.
Key_enumerate_sub_keys (0x0008)	Required to enumerate the subkeys of a registry key.
Key_execute (0x20019)	Equivalent to key_read.
Key_notify (0x0010)	Required to request change specifications for a registry key or for subkeys of a registry key.
Key_query_value (0x0001)	Required to query the values of a registry key.
Key_read (0x20019)	Combines the standard_rights_read, key_query_value, key_enumerate_sub_keys, and key_policy values.
Key_set_value (0x0002)	Required to create, delete, or set a registry value.
Key_wow64_32key (0x0200)	Indicates that an application on 64-bit windows shoshould operate on the 32-bit registry view. For more information, see accessing an alternate registry view.
	This flag must be combined using the OR operator with the other flags in this table that either query or access registry values.
Key_wow64_64key (0x0100)	Indicates that an application on 64-bit windows shoshould operate on the 64-bit registry view. For more information, see accessing an alternate registry view.
	This flag must be combined using the OR operator with the other flags in this table that either query or access registry values.
Key_write (0x20006)	Combines the standard_rights_write, key_set_value, and key_create_sub_key access rights.

Phkresult
An output parameter pointing to a variable that is used to save the handle that opens the registry key. If the returned handle is no longer used, call regclosekey to close it.

Return Value:
Error_success indicates that the function is successfully executed, and a non-zero value indicates that the function fails to be executed. To obtain the error description, call the formatmessage function and input the format_message_from_system parameter.

Note:
Unlike regcreatekeyex, The regopenkeyex function does not create a new key when the key to be opened does not exist.

Requirements

Client	Requires Windows "Longhorn", Windows XP, Windows 2000 Professional, Windows NT Workstation, Windows ME, Windows 98, or Windows 95.
Server	Requires Windows Server "Longhorn", Windows Server 2003, Windows 2000 server, or Windows NT Server.
Header	Declared in winreg. h; Include windows. h.
Library	Link to advapi32.lib.
DLL	Requires advapi32.dll.
Unicode	ImplementedRegopenkeyexw(UNICODE) andRegopenkeyexa(ANSI). Note that Unicode support on Windows ME/98/95 requires Microsoft layer for Unicode.