## 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 of 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
  Identifies 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 only: HKEY_PERFORMANCE_DATA
  Windows 95 only: 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 and Windows 95 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.
  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: Use version 3.1 or later.
Windows: Use Windows 95 or later.
Windows CE: Use version 1.0 or later.
Header: Declared in winreg.h.
Import Library: Use advapi32.lib.