RegEnumKey

The RegEnumKey function enumerates subkeys of the specified open registry key. The function retrieves the name of one subkey each time it is called. This function is provided for compatibility with Windows version 3.1. Win32-based applications should use the RegEnumKeyEx function.

LONG RegEnumKey(
  HKEY hKey,     // handle to key to query
  DWORD dwIndex, // index of subkey to query
  LPTSTR lpName, // address of buffer for subkey name
  DWORD cbName   // size of subkey buffer
);
 

Parameters

hKey

Handle to a currently open key or one of the following predefined reserved handle values:

HKEY_CLASSES_ROOT
HKEY_CURRENT_CONFIG
HKEY_CURRENT_USER
HKEY_LOCAL_MACHINE
HKEY_USERS
Windows NT: HKEY_PERFORMANCE_DATA
Windows 95 and Windows 98: HKEY_DYN_DATA

The keys returned are relative to the key identified by hKey.

dwIndex

Specifies the index of the subkey to retrieve. This value should be zero for the first call to the RegEnumKey function and then incremented for subsequent calls.

Because subkeys are not ordered, any new subkey will have an arbitrary index. This means that the function may return subkeys in any order.

lpName

Pointer to a buffer that receives the name of the subkey, including the terminating null character. This function copies only the name of the subkey, not the full key hierarchy, to the buffer.

cbName

Specifies the size, in characters, of the buffer pointed to by the lpName parameter, in characters. To determine the required buffer size, use the RegQueryInfoKey function to determine the size of the largest subkey for the key identified by the hKey parameter. The maximum required buffer size is (MAX_PATH + 1) characters.

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

To enumerate subkeys, an application should initially call the RegEnumKey function with the dwIndex parameter set to zero. The application should then increment the dwIndex parameter and call the RegEnumKey function until there are no more subkeys (until the function returns ERROR_NO_MORE_ITEMS).

The application can also set dwIndex to the index of the last key on the first call to the function and decrement the index until the subkey with index 0 is enumerated. To retrieve the index of the last subkey, use the RegQueryInfoKey.

While an application is using the RegEnumKey function, it should not make calls to any registration functions that might change the key being queried.

The key identified by the hKey parameter must have been opened with KEY_ENUMERATE_SUB_KEYS access (KEY_READ access includes KEY_ENUMERATE_SUB_KEYS access). To open the key, use the RegCreateKeyEx or RegOpenKeyEx function.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in winreg.h.
  Import Library: Use advapi32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT.

See Also

Registry Overview, Registry Functions, RegCloseKey, RegCreateKeyEx, RegDeleteKey, RegEnumKeyEx, RegOpenKeyEx, RegQueryInfoKey, RegQueryValue