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Windows Embedded CE 6.0 R3


This function stores data in the value field of an open registry key. It can also set additional value and type information for the specified key.

A remote application interface (RAPI) version of this function exists called CeRegSetValueEx (RAPI).


LONG RegSetValueEx(
  HKEY hKey,
  LPCWSTR lpValueName,
  DWORD Reserved,
  DWORD dwType,
  const BYTE* 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, this function adds it to the key. If this parameter is set to NULL or an empty string, the value set is the value named "Default". The maximum length of a value name is 255, not including the terminating NULL character.
  • Reserved
    [in] Reserved. Must be set to zero.
  • dwType
    [in] Type of information to be stored as the value data. The following table shows possible values.

    Value Description


    Specifies binary data in any form.


    Specifies a 32-bit number.


    Specifies a 32-bit number in big-endian format.

    In big-endian format, a multibyte value is stored in memory from the highest byte to the lowest byte. For example, the value 0x12345678 is stored as (0x12 0x34 0x56 0x78) in big-endian format.


    Specifies a 32-bit number in little-endian format. This is equivalent to REG_DWORD.

    In little-endian format, a multibyte value is stored in memory from the lowest byte to the highest byte. For example, the value 0x12345678 is stored as (0x78 0x56 0x34 0x12) in little-endian format.


    Specifies a null-terminated string that contains unexpanded references to environment variables, for example, %PATH%.


    Specifies a Unicode symbolic link. Used internally. Applications do not use this type.


    Specifies an array of null-terminated strings, terminated by two null characters.


    No defined value type.


    Specifies a device-driver resource list.


    Specifies a null-terminated Unicode string. Do not use the REG_SZ type to store hard-coded paths to the system root.

  • lpData
    [in] Pointer to a buffer that contains the data to be stored with the specified value name.
  • cbData
    [in] Size, in bytes, of the information pointed to by lpData. If the data is of type REG_SZ, REG_EXPAND_SZ, or REG_MULTI_SZ, This parameter must include the size of the terminating null character. The maximum size of data allowed 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. The message resource is optional, so FormatMessage might fail.


Value lengths are limited by available memory. Long values of more than 2048 bytes should be stored as files with the file names stored in the registry for efficiency. Application elements, such as icons, bitmaps, and executable files, should be stored as files, and not be placed in the registry.

Windows Mobile supports only the Unicode version of this function.


Header winreg.h
Library coredll.lib
Windows Embedded CE Windows CE 1.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also


Registry Functions

Other Resources

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