Microsoft KB Archive/135398

= How to write to the Windows registry by using Windows API calls =

Article ID: 135398

Article Last Modified on 2/2/2005

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APPLIES TO


 * Microsoft Visual FoxPro 3.0 Standard Edition
 * Microsoft Visual FoxPro 5.0 Standard Edition
 * Microsoft Visual FoxPro 6.0 Professional Edition
 * Microsoft Visual FoxPro 7.0 Professional Edition
 * Microsoft Visual FoxPro 8.0 Professional Edition
 * Microsoft Visual FoxPro 9.0 Professional Edition

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This article was previously published under Q135398



SUMMARY
You can write information directly to the Microsoft Windows 95, Windows NT, or Win32 registry. The Windows registry is the suggested place for 32-bit applications to store application information. Previous versions of Windows used .INI files for this purpose. This article gives a brief description of the Windows registry and the steps necessary to write information to it programatically.



MORE INFORMATION
The following information comes from Chapter 10 of the Windows NT Resource Kit:

The registry is analogous to the .INI files used under Windows 3.1, with each key in the registry similar to a bracketed heading in an .INI file, and entries under the heading similar to values in the registry. However, registry keys can contain subkeys, while .INI files do not support nested headings. Registry values can also consist of executable code, rather than the simple strings representing values in .INI files. And individual preferences for multiple users of the same computer can be stored in the registry, which is not possible with .INI files.

Windows NT registry
The registry is a database of keys and values. The Windows NT registry contains four primary keys: HKEY_CLASSES_ROOT  - File associations and DDE/OLE actions.

HKEY_LOCAL_MACHINE - Global information on the state of the local computer.

HKEY_USERS         - Configuration information about each individual user of the computer and the DEFAULT entry.

HKEY_CURRENT_USER  - specific key within HKEY_USERS that stores information for the currently active user.

Windows 95 registry
Windows 95 adds a couple more primary keys: HKEY_CURRENT_CONFIG - Hardware configuration for devices currently attached and installed on the computer.

HKEY_DYN_DATA      - System Monitor data for performance settings and statistics.

It is good idea for applications to store version specific information in the HKEY_LOCAL_MACHINE\SOFTWARE branch in this format:   SOFTWARE\Vendor\product\version The example code in this article shows one way to register an application name and version.

Win32s registry
The Win32s registry is limited to only one hive, HKEY_CLASSES_ROOT, and all keys are children of that hive. Any information placed in the Win32s registry should be placed in a child key of HKEY_CLASSES_ROOT instead of HKEY_CLASSES_ROOT (used in Windows 95 and Windows NT).

Sample code
The following code illustrate the ability to create a new registry key by using the Windows API RegCreateKeyEx and to assign a value to that key by using RegSetValueEx. These 32bit functions are first prototyped using the DECLARE command; then they are available to be called directly. For more information, search for DECLARE - DLL in the Help menu.

Note Some constants are declared with definitions taken from the appropriate Microsoft Visual C++ header files. * REGISTRY.PRG
 * This code writes information to the HKEY_LOCAL_MACHINE\SOFTWARE key.
 * It creates a key called MYAPPS, and a value name called AppName that
 * contains the value "SuperApp 1.0"

PUBLIC RESULT,DISPLAY RESULT=0 DISPLAY=0
 * 1) DEFINE HKEY_LOCAL_MACHINE 2147483650  && (HKEY) 0x80000002
 * 2) DEFINE SECURITY_ACCESS_MASK 983103    && SAM value KEY_ALL_ACCESS

DECLARE RegCreateKeyEx IN ADVAPI32.DLL; INTEGER,STRING,INTEGER,STRING,INTEGER,INTEGER,INTEGER,INTEGER @, INTEGER @ DECLARE RegSetValueEx IN ADVAPI32.DLL; INTEGER,STRING,INTEGER,INTEGER,STRING,INTEGER

?RegCreateKeyEx(HKEY_LOCAL_MACHINE,"SOFTWARE\MYAPPS",0,"REG_SZ",; 0,SECURITY_ACCESS_MASK,0,@RESULT,@DISPLAY) && Returns .T. if successful ?RESULT                                    && Returns the key handle ?DISPLAY                                   && Returns one of 2 values: && REG_CREATE_NEW_KEY = 1 && REG_OPENED_EXISTING_KEY = 2 ?RegSetValueEx(RESULT,"AppName",0,1,"SuperApp 1.0",13)