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.

Note  This function is provided only for compatibility with 16-bit versions of Windows. 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, // buffer for subkey name
  DWORD cbName   // size of subkey name buffer
);

Parameters

hKey

[in] 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/2000: HKEY_PERFORMANCE_DATA
Windows 95/98: HKEY_DYN_DATA

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

dwIndex

[in] 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

[out] 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

[in] Specifies the size, in TCHARs, of the buffer pointed to by the lpName parameter. 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.

Windows 95/98: No registry subkey or value name may exceed 255 characters.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Requires Windows 95 or later.
  Header: Declared in Winreg.h; include Windows.h.
  Library: Use Advapi32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT/2000.

See Also

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