RegSetKeyValueA function (winreg.h)

Sets the data for the specified value in the specified registry key and subkey.


LSTATUS RegSetKeyValueA(
  [in]           HKEY    hKey,
  [in, optional] LPCSTR  lpSubKey,
  [in, optional] LPCSTR  lpValueName,
  [in]           DWORD   dwType,
  [in, optional] LPCVOID lpData,
  [in]           DWORD   cbData


[in] hKey

A handle to an open registry key. The key must have been opened with the KEY_SET_VALUE access right. For more information, see Registry Key Security and Access Rights.

This handle is returned by the RegCreateKeyEx, RegCreateKeyTransacted, RegOpenKeyEx, or RegOpenKeyTransacted function. It can also be one of the following predefined keys:


[in, optional] lpSubKey

The name of the subkey relative to the key identified by hKey. If the subkey does not exist, it is created as a non-volatile key with a default security descriptor. If this parameter is NULL, then the value is created in the key specified by hKey.

[in, optional] lpValueName

The name of the registry value whose data is to be updated.

[in] dwType

The type of data pointed to by the lpData parameter. For a list of the possible types, see Registry Value Types.

[in, optional] lpData

The data to be stored with the specified value name.

For string-based types, such as REG_SZ, the string must be null-terminated. With the REG_MULTI_SZ data type, the string must be terminated with two null characters.

[in] cbData

The size of the information pointed to by the lpData parameter, in bytes. 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 or characters.

Return value

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.


To compile an application that uses this function, define _WIN32_WINNT as 0x0600 or later. For more information, see Using the Windows Headers.


The winreg.h header defines RegSetKeyValue as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.


Requirement Value
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2008 [desktop apps only]
Target Platform Windows
Header winreg.h (include Windows.h)
Library Advapi32.lib
DLL Advapi32.dll

See also


Registry Functions