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,     // address of buffer for value string
  LPDWORD lpcbValueName,  // address for size of value buffer
  LPDWORD lpReserved,     // reserved
  LPDWORD lpType,         // address of buffer for type code
  LPBYTE lpData,          // address of buffer for value data
  LPDWORD lpcbData        // address for size of data 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 enumerated values are associated with the key identified by hKey.

dwIndex

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

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

lpcbValueName

Pointer to a variable that specifies the size, in characters, 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 lpcbValueName 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

Pointer to a variable that receives the type code for the value entry. The type code can be one of the following values:

Value	Meaning
REG_BINARY	Binary data in any form.
REG_DWORD	A 32-bit number.
REG_DWORD_LITTLE_ENDIAN	A 32-bit number in little-endian format. This is equivalent to REG_DWORD. In little-endian format, a multi-byte value is stored in memory from the lowest byte (the "little end") to the highest byte. For example, the value 0x12345678 is stored as (0x78 0x56 0x34 0x12) in little-endian format. Windows NT, Windows 95, and Windows 98 are designed to run on little-endian computer architectures. A user may connect to computers that have big-endian architectures, such as some UNIX systems.
REG_DWORD_BIG_ENDIAN	A 32-bit number in big-endian format. In big-endian format, a multi-byte value is stored in memory from the highest byte (the "big end") to the lowest byte. For example, the value 0x12345678 is stored as (0x12 0x34 0x56 0x78) in big-endian format.
REG_EXPAND_SZ	A null-terminated string that contains unexpanded references to environment variables (for example, "%PATH%"). It will be a Unicode or ANSI string depending on whether you use the Unicode or ANSI functions. To expand the environment variable references, use the ExpandEnvironmentStrings function.
REG_LINK	A Unicode symbolic link.
REG_MULTI_SZ	An array of null-terminated strings, terminated by two null characters.
REG_NONE	No defined value type.
REG_RESOURCE_LIST	A device-driver resource list.
REG_SZ	A null-terminated string. It will be a Unicode or ANSI string, depending on whether you use the Unicode or ANSI functions.

The lpType parameter can be NULL if the type code is not required.

lpData

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

lpcbData

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.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Requires version 1.0 or later.
  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, RegCreateKeyEx, RegEnumKey, RegEnumKeyEx, RegOpenKeyEx, RegQueryInfoKey