RegSetValueEx

The RegSetValueEx function sets the data and type of a specified value under a registry key.

Declaration

Declare Function RegSetValueExLong Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, ByVal lpValue As Long, ByVal cbData As Long) As Long

Variations

Declare Function RegSetValueExLong Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, lpValue As Long, ByVal cbData As Long) As Long

Declare Function RegSetValueExString Lib "advapi32.dll" Alias "RegSetValueExA" (ByVal hKey As Long, ByVal lpValueName As String, ByVal Reserved As Long, ByVal dwType As Long, ByVal lpValue As String, ByVal cbData As Long) As Long

Parameters

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

HKEY_CLASSES_ROOT

HKEY_CURRENT_CONFIG

HKEY_CURRENT_USER

HKEY_USERS

lpValueName
Pointer to a string containing the name of the value to set. If a value with this name is not already present in the key, the function adds it to the key.
If lpValueName is NULL or an empty string, "", the function sets the type and data for the key's unnamed or default value.

Windows 95 and Windows 98: On Windows 95, the type of a key's default value is always REG_SZ, so the dwType parameter must specify REG_SZ for an unnamed value. On Windows 98, an unnamed value can be of any type.

Windows NT: Registry keys do not have default values, but they can have one unnamed value, which can be of any type.

Reserved
Reserved; must be zero.

dwType
Specifies the type of information to be stored as the value's data. This parameter can be one of the following values:

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 theExpandEnvironmentStrings 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.
Do not use the REG_SZ type to store hard-coded paths to the system root directory or to the drive containing the system files. Instead, use the REG_EXPAND_SZ type with environment variables such as "%SystemRoot%". This ensures that the path will be up-to-date even if the user remaps the system drive to a different drive letter.

lpValue
Pointer to a buffer containing the data to be stored with the specified value name.

cbData
Specifies the size, in bytes, of the information pointed to by the lpData parameter. If the data is of type REG_SZ, REG_EXPAND_SZ, or REG_MULTI_SZ, cbData must include the size of the terminating null character.

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