RegEnumValue

The RegEnumValue function enumerates the values for the specified open registry key. The function copies one indexed value name and data block for the key each time it is called.

LONG RegEnumValue(
  HKEY hKey,             // handle to key to query
  DWORD dwIndex,         // index of value to query
  LPTSTR lpValueName,    // value buffer
  LPDWORD lpcValueName,  // size of value buffer
  LPDWORD lpReserved,    // reserved
  LPDWORD lpType,        // type buffer
  LPBYTE lpData,         // data buffer
  LPDWORD lpcbData       // size of data 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 enumerated values are associated with the key identified by hKey.

dwIndex

[in] Specifies the index of the value to retrieve. This parameter should be zero for the first call to the RegEnumValue function and then be incremented for subsequent calls.

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

lpValueName

[out] Pointer to a buffer that receives the name of the value, including the terminating null character.

lpcValueName

[in/out] Pointer to a variable that specifies the size, in TCHARs, of the buffer pointed to by the lpValueName parameter. This size should include the terminating null character. When the function returns, the variable pointed to by lpcValueName contains the number of characters stored in the buffer. The count returned does not include the terminating null character.

lpReserved

Reserved; must be NULL.

lpType

[out] Pointer to a variable that receives a code indicating the type of data stored in the specified value. For a list of the possible type codes, see Registry Value Types. The lpType parameter can be NULL if the type code is not required.

lpData

[out] Pointer to a buffer that receives the data for the value entry. This parameter can be NULL if the data is not required.

lpcbData

[in] Pointer to a variable that specifies the size, in bytes, of the buffer pointed to by the lpData parameter. When the function returns, the variable pointed to by the lpcbData parameter contains the number of bytes stored in the buffer. This parameter can be NULL, only if lpData is NULL.

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

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

While using RegEnumValue, an application should not call any registration functions that might change the key being queried.

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

To determine the maximum size of the name and data buffers, use the RegQueryInfoKey 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, RegCreateKeyEx, RegEnumKey, RegEnumKeyEx, RegOpenKeyEx, RegQueryInfoKey