CeRegSetValueEx (RAPI)

A version of this page is also available for

Windows Embedded CE 6.0 R3


This function stores data in the value field of an open registry key on a remote Windows Embedded CEā€“based device. It can also set additional value and type information for the specified key.


LONG CeRegSetValueEx (
  HKEY hKey,
  LPCWSTR lpValueName,
  DWORD Reserved,
  DWORD dwType,
  LPBYTE lpData,
  DWORD cbData


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





  • lpValueName
    [in] 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 this parameter is NULL or an empty string, the function sets the type and data for the key's unnamed value. Registry keys do not have default values, but they can have one unnamed value, which can be of any type. The maximum length of a value name is 255, not including the terminating NULL character.
  • Reserved
    [in] Reserved; must be zero.
  • dwType
    [in] Specifies the type of information to be stored as the value's data. This parameter can be one of the following values.

    Value Description


    Binary data in any form.


    A 32-bit number.


    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.


    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.


    A null-terminated string that contains unexpanded references to environment variables (for example, "%PATH%").


    A Unicode symbolic link. Used internally; applications should not use this type.


    An array of null-terminated strings, terminated by two null characters.


    No defined value type.


    A device-driver resource list.


    A null-terminated string.

    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.

  • lpData
    [in] Pointer to a buffer containing the data to be stored with the specified value name.
  • cbData
    [in] 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. The maximum size of data allowed in Windows Embedded CE is 4 KB.

Return Value

ERROR_SUCCESS indicates success. A nonzero error code defined in Winerror.h indicates failure. To get a generic description of the error, call FormatMessage with the FORMAT_MESSAGE_FROM_SYSTEM flag set.


Value lengths are limited by available memory. Long values (more than 2048 bytes) should be stored as files with the file names stored in the registry. This helps the registry perform efficiently. Application elements such as icons, bitmaps, and executable files should be stored as files and not be placed in the registry.

The key identified by the hKey parameter must have been opened with KEY_SET_VALUE access. To open the key, use the CeRegCreateKeyEx or CeRegOpenKeyEx function.


Header rapi.h
Library rapi.lib
Windows Embedded CE Windows CE 3.0 and later
Windows Mobile Pocket PC 2002 and later, Smartphone 2002 and later

See Also


RAPI Functions
CeRegCreateKeyEx (RAPI)
CeRegOpenKeyEx (RAPI)
CeRegQueryValueEx (RAPI)