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Another registry class

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25 Apr 2003CPOL2 min read 185.8K   2.6K   63   59
A registry class with overloaded operators to use registry values like normal variables

Introduction

In many projects I need to store simple strings, DWORDS or for window position CRect's in the registry. I know there are many registry classes out there, so why one more?

The answer: simplicity. I want to write to the registry as easy as assigning a value to a variable. Like an eeprom variable in neuron controllers (those of you who use those controllers know what I mean). So I wrote exactly such a class.

Usage

So, how to use this class - or better classes. I wrote a separate class for CString, DWORD, CRect and CPoint.

// initialize the variables
CRegString mystring("Software\\Company\\Subkey\\MyString", "defaultvalue");
CRegRect   myrect("Software\\Company\\Subkey\\MyRect", CRect(1,1,1,1));
CRegDWORD  myword("Software\\Company\\Subkey\\mydword", 100, 
                     TRUE, HKEY_LOCAL_MACHINE);
CRegPoint  mypoint("Software\\Company\\Subkey\\mypoint");

// now use those variables
CString str = mystring;     //if registry does not exist, the default value is used
mystring = "TestValue";     //"TestValue" is stored in the registry
mystring += "!";            //now the registry value MyString contains "TestValue!"
myrect = CRect(100,200,300,400);    //store in the registry
LPRECT lpR = (LPRECT)myrect;
myword = GetTickCounts();   //just an example
mypoint = CPoint(0,0);

As you can see, once the CRegXXX object knows to which registry key/value it is assigned to you can use it like any other variable!

To avoid too much access to the registry the value is cached. Writes occur only if the new value is different than the current value. Reads occur only once in the constructor. Since such a cached behaviour could lead to some problems, you can force reads and writes to the registry with the methods read() and write(). To disable the cache and force the class to always access the registry just set that in the constructor. the constructor for the CRegDWORD looks like this:

/**
* Constructor.
* @param key the path to the key, including the key. 
*            example: "Software\\Company\\SubKey\\MyValue"
* @param def the default value used when the key does not exist or 
*            a read error occured
* @param force set to TRUE if no cache should be used, i.e. always read and write 
*              directly from/to registry
* @param base a predefined base key like HKEY_LOCAL_MACHINE. see the SDK 
*             documentation for more information.
*/
CRegDWORD(CString key, DWORD def = 0, BOOL force = FALSE, 
          HKEY base = HKEY_CURRENT_USER);

The classes CRegString, CRegRect and CRegPoint have similar constructors. See the header files for details.

Not all methods of the "base" classes are overloaded. So if you want to, for example, use some methods of the CString class you have to typecast the CRegString to a CString first:

int l = ((CString)mystring).GetLength();
((CString)mystring).Trim();

Please note that in the second line where the Trim() is used that the changed string is NOT written to the registry!

And please: keep your complaints about "not again a registry class" and the like for yourselves. If you don't like it, don't use it!

Update

  • 2. April 2003 :
    1. added classes for use without MFC: CRegStdString, CRegStdDWORD
    2. now compiles for UNICODE too
  • 9. July 2002 :
    1. Corrected a bug found by Hans Dietrich
    2. Extended the classes with two methods: removeKey() and removeValue()

Daniel Andersson wrote a templatized version of this class. See his article here.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Software Developer
Switzerland Switzerland
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Comments and Discussions

 
Generalloading .reg file programmatically Pin
bruno leclerc18-Mar-04 1:14
bruno leclerc18-Mar-04 1:14 
GeneralCRegStdDWORD instead of CRegStdWORD Pin
ujohnc0016-Mar-04 10:11
ujohnc0016-Mar-04 10:11 
GeneralGreat! thank you Pin
PMartos18-Dec-03 9:14
PMartos18-Dec-03 9:14 
GeneralFelicidades :) Pin
Torres O.17-Dec-03 8:41
Torres O.17-Dec-03 8:41 
QuestionBug? Pin
Igor Vigdorchik16-Dec-03 9:29
Igor Vigdorchik16-Dec-03 9:29 
AnswerRe: Bug? Pin
Jonas Nordlund5-Feb-04 23:50
Jonas Nordlund5-Feb-04 23:50 
GeneralRe: Bug? Pin
Igor Vigdorchik6-Feb-04 18:03
Igor Vigdorchik6-Feb-04 18:03 
GeneralDid not compile with VC6 Pin
Jacques Cooper12-Dec-03 13:16
Jacques Cooper12-Dec-03 13:16 
GeneralRe: Did not compile with VC6 Pin
Jonas Nordlund5-Feb-04 23:55
Jonas Nordlund5-Feb-04 23:55 
Generalcool code... a lot of thanks and a suggestion... Pin
pHreak081528-Sep-03 4:11
pHreak081528-Sep-03 4:11 
GeneralGreat Pin
BEamer18-Sep-03 19:32
BEamer18-Sep-03 19:32 
GeneralHere's how to read/write to REG_MULTI_SZ Pin
Paul Groetzner10-Aug-03 18:13
Paul Groetzner10-Aug-03 18:13 
GeneralRe: Here's how to read/write to REG_MULTI_SZ Pin
jfernb3-Jun-04 11:07
sussjfernb3-Jun-04 11:07 
GeneralRe: Here's how to read/write to REG_MULTI_SZ Pin
Paul Groetzner22-Dec-04 7:15
Paul Groetzner22-Dec-04 7:15 
GeneralRe: Here's how to read/write to REG_MULTI_SZ Pin
MoSs.gr3-Nov-04 7:56
MoSs.gr3-Nov-04 7:56 
GeneralRe: Here's how to read/write to REG_MULTI_SZ Pin
farzadb8-Apr-05 12:31
farzadb8-Apr-05 12:31 
QuestionHow to use as a member variable? Pin
Sorak26-May-03 19:40
Sorak26-May-03 19:40 
AnswerRe: How to use as a member variable? Pin
SteveKing26-May-03 23:04
SteveKing26-May-03 23:04 
AnswerRe: How to use as a member variable? Pin
Chris Richardson27-May-03 16:47
Chris Richardson27-May-03 16:47 
GeneralBeautiful Pin
Abin1-Apr-03 2:51
Abin1-Apr-03 2:51 
Generala little problem working with UNICODE Pin
nothingremained10-Nov-02 20:16
nothingremained10-Nov-02 20:16 
GeneralRe: a little problem working with UNICODE Pin
TDWiseley8-Jan-03 14:11
TDWiseley8-Jan-03 14:11 
GeneralTrim Pin
Dins_C10-Sep-02 10:20
Dins_C10-Sep-02 10:20 
GeneralRe: Trim Pin
SteveKing11-Sep-02 3:00
SteveKing11-Sep-02 3:00 
GeneralCould you help me please! Pin
Anonymous14-Jul-02 18:14
Anonymous14-Jul-02 18:14 

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