RegCreateKeyExA function (winreg.h)

Creates the specified registry key. If the key already exists, the function opens it. Note that key names are not case sensitive.

To perform transacted registry operations on a key, call the RegCreateKeyTransacted function.

Applications that back up or restore system state including system files and registry hives should use the Volume Shadow Copy Service instead of the registry functions.

Syntax

LSTATUS RegCreateKeyExA(
  [in]            HKEY                        hKey,
  [in]            LPCSTR                      lpSubKey,
                  DWORD                       Reserved,
  [in, optional]  LPSTR                       lpClass,
  [in]            DWORD                       dwOptions,
  [in]            REGSAM                      samDesired,
  [in, optional]  const LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  [out]           PHKEY                       phkResult,
  [out, optional] LPDWORD                     lpdwDisposition
);

Parameters

[in] hKey

A handle to an open registry key. The calling process must have KEY_CREATE_SUB_KEY access to the key. For more information, see Registry Key Security and Access Rights.

Access for key creation is checked against the security descriptor of the registry key, not the access mask specified when the handle was obtained. Therefore, even if hKey was opened with a samDesired of KEY_READ, it can be used in operations that modify the registry if allowed by its security descriptor.

This handle is returned by the RegCreateKeyEx or RegOpenKeyEx function, or it can be one of the following predefined keys:

HKEY_CLASSES_ROOT

HKEY_CURRENT_CONFIG

HKEY_CURRENT_USER

HKEY_LOCAL_MACHINE

HKEY_USERS

[in] lpSubKey

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; it can be up to 32 levels deep in the registry tree. For more information on key names, see Structure of the Registry.

If lpSubKey is a pointer to an empty string, phkResult receives a new handle to the key specified by hKey.

This parameter cannot be NULL.

Reserved

This parameter is reserved and must be zero.

[in, optional] lpClass

The user-defined class type of this key. This parameter may be ignored. This parameter can be NULL.

[in] dwOptions

This parameter can be one of the following values.

[in] samDesired

A mask that specifies the access rights for the key to be created. For more information, see Registry Key Security and Access Rights.

[in, optional] lpSecurityAttributes

A 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.

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. The ACLs in a default security descriptor for a key are inherited from its direct parent key.

[out] phkResult

A pointer to a variable that receives a handle to the opened or created key. If the key is not one of the predefined registry keys, call the RegCloseKey function after you have finished using the handle.

[out, optional] lpdwDisposition

A pointer to a variable that receives one of the following disposition values.

If lpdwDisposition is NULL, no disposition information is returned.

Return value

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 RegSetValueEx function to set key values.

The RegCreateKeyEx function creates all missing keys in the specified path. An application can take advantage of this behavior to create several keys at once. For example, an application can create a subkey four levels deep at the same time as the three preceding subkeys by specifying a string of the following form for the lpSubKey parameter:

subkey1\subkey2\subkey3\subkey4

Note that this behavior will result in creation of unwanted keys if an existing key in the path is spelled incorrectly.

An application cannot create a key that is a direct child of HKEY_USERS or HKEY_LOCAL_MACHINE. An application can create subkeys in lower levels of the HKEY_USERS or HKEY_LOCAL_MACHINE trees.

If your service or application impersonates different users, do not use this function with HKEY_CURRENT_USER. Instead, call the RegOpenCurrentUser function.

Note that operations that access certain registry keys are redirected. For more information, see Registry Virtualization and 32-bit and 64-bit Application Data in the Registry.

Requirements

See also

RegCloseKey

RegDeleteKey

RegOpenKeyEx

RegSaveKey

Registry Functions

Registry Overview

SECURITY_ATTRIBUTES