RegSetValue

RegSetValue

The RegSetValue function associates a value with a specified key. This value must be a text string and cannot have a name. This function is provided for compatibility with Windows version 3.1. Win32-based applications should use the RegSetValueEx function, which allows an application to set any number of named values of any data type.

LONG RegSetValue(

HKEY hKey,	// handle of key to set value for
LPCTSTR lpSubKey,	// address of subkey name
DWORD dwType,	// type of value
LPCTSTR lpData,	// address of value data
DWORD cbData	// size of value data
);

Parameters

hKey

Identifies a currently open key or any of the following predefined reserved handle values:

HKEY_CLASSES_ROOT
HKEY_CURRENT_USER
HKEY_LOCAL_MACHINE
HKEY_USERS

lpSubKey

Points to a null-terminated string containing the name of the subkey with which a value is associated. This parameter can be null or a pointer to an empty string. In this case, the value will be added to the key identified by the hKey parameter.

dwType

Specifies the type of information to be stored. This parameter must be the REG_SZ type. To store other data types, use the RegSetValueEx function.

lpData

Points to a null-terminated string containing the value to set for the specified key.

cbData

Specifies the length, in bytes, of the string pointed to by the lpData parameter, not including the terminating null character.

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

If the key specified by the lpSubKey parameter does not exist, the RegSetValue function creates it.

Value lengths are limited by available memory. Long values (more than 2048 bytes) should be stored as files with the filenames stored in the registry. This helps the registry perform efficiently.

The key identified by the hKey parameter must have been opened with KEY_SET_VALUE access. To open the key, use the RegCreateKeyEx or RegOpenKeyEx function. If the ANSI version of this function is used (either by explicitly calling RegSetValue or by not defining Unicode before including the WINDOWS.H file), the lpData parameter must be an ANSI character string. The string is converted to Unicode before it is stored in the registry.