A Registry Class

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• Overview
• The CRegistry Class
  • OpenKey
  • CreateKey
  • DeleteKey
  • GetValue
  • SetValue
  • DeleteValue
  • CloseKey

Overview

I created this class to make it easy to work with the Registry. For this I created the CRegistry class.

The CRegistry Class

The CRegistry class has a set of functions that make using the registry easy.

CRegistry::OpenKey

The OpenKey opens the specified registry key.

BOOL OpenKey(enum Keys hKey, LPCTSTR szKey);

Parameters

enum Keys hKey - Handle to any of the following predefined values:

CRegistry::classesRoot

CRegistry::currentUser

CRegistry::localMachine

CRegistry::currentConfig

CRegistry::users

Windows NT/2000: CRegistry::performanceData

Windows 95/98: CRegistry::dynData

LPCTSTR szKey - Pointer to a null-terminated string containing the name of the key to open.

If the function succeeds, this returns TRUE.

See sample

"Sample1">
  CRegistry pReg;
  
  pReg.OpenKey(CRegistry::currentUser, "Entry1\\carlos1");
  CString str = _T("");

  if(pReg.GetValue("SZVAL1", str))
    AfxMessageBox("The Value SZVAL1 don't exists", MB_ICONWARNING);
    
  DWORD dwVal = 0;
  pReg.GetValue("DWVAL", dwVal);

  pReg.GetValue(NULL, str);
  pReg.CloseKey();

CRegistry::CreateKey

The CreateKey function creates the specified registry key. If the key already exists in the registry, the function opens it.

BOOL CreateKey(enum Keys hKey, LPCTSTR szKey);

Parameters

enum Keys hKey - Handle to any of the following predefined values:

CRegistry::classesRoot

CRegistry::currentUser

CRegistry::localMachine

CRegistry::currentConfig

CRegistry::users

Windows NT/2000: CRegistry::performanceData

Windows 95/98: CRegistry::dynData

LPCTSTR szKey - Pointer to a null-terminated string containing the name of the key to open or create.

If the function succeeds, this returns TRUE.

CRegistry::DeleteKey

The DeleteKey function deletes a subkey.

BOOL DeleteKey(enum Keys hKey, LPCTSTR szKey);

Parameters

enum Keys hKey - Handle to any of the following predefined values:

CRegistry::classesRoot

CRegistry::currentUser

CRegistry::localMachine

CRegistry::currentConfig

CRegistry::users

Windows NT/2000: CRegistry::performanceData

Windows 95/98: CRegistry::dynData

LPCTSTR szKey - Pointer to a null-terminated string containing the name of the key to delete.

If the function succeeds, this returns TRUE.

CRegistry::GetValue

The GetValue function retrieves the data for a specified value name from the open registry key.

BOOL GetValue(LPCTSTR lpValueName, CString& strValue);
BOOL GetValue(LPCTSTR lpValueName, DWORD& dwValue);

Parameters

LPCTSTR lpValueName - Pointer to a null-terminated string containing the name of the value to get

CString& strValue - Pointer to a buffer that receives the value's data

DWORD& dwValue - Pointer to a buffer that receives the value's data

If the function succeeds, this returns TRUE.

See sample

CRegistry::SetValue

The SetValue function sets the data and type of a specified value under a registry key.

BOOL SetValue(LPCTSTR lpValueName, LPCTSTR lpData);
BOOL SetValue(LPCTSTR lpValueName, DWORD dwValue);

Parameters

LPCTSTR lpValueName - Pointer to a null-terminated string containing the name of the value to set

CString& strValue - Pointer to a buffer containing the data to be stored with the specified value name

DWORD& dwValue - Pointer to a buffer containing the data to be stored with the specified value name

If the function succeeds, this returns TRUE.

See sample

"Sample2">pReg.OpenKey(CRegistry::currentUser, "Entry1\\carlos1");

pReg.SetValue("SZVAL", "STRVAL");
pReg.SetValue(NULL, "default");
pReg.SetValue("DWVAL", 34); 

pReg.CloseKey();

CRegistry::DeleteValue

The DeleteValue function removes a named value from the specified registry key

BOOL DeleteValue(LPCTSTR lpValueName);

Parameters

LPCTSTR lpValueName - Pointer to a null-terminated string that names the value to remove.

If the function succeeds, this returns TRUE.

See sample

"Sample3">  CRegistry pReg;

  pReg.OpenKey(CRegistry::currentUser, "Entry1\\carlos1");

  pReg.DeleteValue("SZVAL");	
  pReg.CloseKey();

CRegistry::CloseKey

The CloseKey function closes the registry key.

void CloseKey();

See sample

Updates

04 August 2001: Version 1.0 Released.

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error C2872: 'ULONG_PTR' : ambiguous symbol Pooh Agarwal 21:50 17 Oct '06   Hi, While using HKEY_LOCAL_MACHINE in RegOpenKey method, I get following error message - error C2872: 'ULONG_PTR' : ambiguous symbol could be 'd:\microsoft visual studio 8\vc\platformsdk\include\basetsd.h(123) : __w64 unsigned long ULONG_PTR'or 'd:\usbproject\debug\dte80a.tlh(463) : EnvDTE::ULONG_PTR' I have included EnvDTE namespace in the file. Could someone help me in detecting what is wrong? Thanks in advance. Poonam Sign In·View Thread·PermaLink 1.75/5 (3 votes) Re: error C2872: 'ULONG_PTR' : ambiguous symbol Vider 4:33 22 Nov '07   replace the symbol on you import directive: #import "libid:80cc9f66-e7d8-4ddd-85b6-d9e6cd0e93e2" version("8.0") lcid("0") raw_interfaces_only named_guids rename("ULONG_PTR","ULONG_PTRDTE") Sign In·View Thread·PermaLink 2.00/5 (1 vote) bug fix for VC7/8 [modified] waldermort 9:16 4 Oct '06   Change the keys enum to the following: enum Keys { classesRoot = (LONG)(ULONG_PTR)HKEY_CLASSES_ROOT, currentUser = (LONG)(ULONG_PTR)HKEY_CURRENT_USER, localMachine = (LONG)(ULONG_PTR)HKEY_LOCAL_MACHINE, users = (LONG)(ULONG_PTR)HKEY_USERS, performanceData = (LONG)(ULONG_PTR)HKEY_PERFORMANCE_DATA, //Windows NT/2000 currentConfig = (LONG)(ULONG_PTR)HKEY_CURRENT_CONFIG, dynData = (LONG)(ULONG_PTR)HKEY_DYN_DATA //Windows 95/98 }; -- modified at 14:35 Wednesday 4th October, 2006 Sign In·View Thread·PermaLink 1.00/5 (1 vote) Thank you msanchezv 2:25 30 Jan '06   For me it works just fine, and it's very useful Sign In·View Thread·PermaLink Memory leak jmaccelari 21:45 19 Jul '04   In the method BOOL CRegistry::GetValue(LPCTSTR lpValueName, CString& strValue), the variable lpstrValue is malloc()'ed but not free()'ed. This results in a memory leak each time it is called. Solution is to add: free(lpstrValue); just before the return. Even better - replace the malloc with new and the free with delete (this is supposedly C++ after all!). Sign In·View Thread·PermaLink can't get it to work (noob!) E-Male 1:13 19 May '04   i tried to add this clase to a program (that for does nothing) i use ms visual studio .net 2003 c++, but i'm very new to it so my question is: can i just add this class or do i have to include other stuff or add a namespace or...? if there is nothing more to add: is there anything to be carefull about when adding classes to a visual studio project? (i only learned command line g++) thx in advance E-Male Sign In·View Thread·PermaLink 5.00/5 (1 vote) Almost perfect! Terry O'Nolley 16:23 15 May '04   First off - thanks for simplifying the registry. I am working on my first project where I need to add registry entries and I headed straight for Code Project. I voted this a 5. Sign In·View Thread·PermaLink Re: Almost perfect! Carlos Antollini 16:42 15 May '04   Thanks... Regards Carlos Antollini Do you know piFive[^] ? Sign In·View Thread·PermaLink bug with 2000pro ? alex-pcom 3:17 22 Jan '04   Hello this code works well on WindowsXP but does nothing on 2000 pro : CString value; value.Format("%s", buff); CRegistry regs; if (regs.CreateKey(CRegistry::currentUser, "Software\\xxx")==FALSE) AfxMessageBox("Error CreateKey"); if (regs.CreateKey(CRegistry::currentUser, "Software\\xxx\\yyy")==FALSE) AfxMessageBox("Error CreateKey2"); if (regs.OpenKey(CRegistry::currentUser, "Software\\xxx\\yyy")==FALSE) AfxMessageBox("Error OpenKey"); if (regs.SetValue( "IDVAL", (LPCTSTR) value )==FALSE) AfxMessageBox("Erreur SetValue"); regs.CloseKey(); I have no xxx or yyy keys in registry even after rebooting the system Am I doing something wrong ? Sign In·View Thread·PermaLink Re: bug with 2000pro ? Carlos Antollini 4:36 22 Jan '04   You are not doing something wrong. I tested your code, And I din't find any problem. It,s very strange because I wrote that class over windows 2000 Pro, and Now I'm using a Windows 2000 Advance Server and XP Pro and I didn't find any strange behavior. Check if you have any permits problem over the registry, or something like that.... Best Regards Carlos Antollini Do you know piFive[^] ? Sign In·View Thread·PermaLink Re: bug with 2000pro ? Shikamaru 22:03 27 Apr '04   I've got the same prob.Neway,how do i check my registry permit?? Thanx in advance. 3.142 Sign In·View Thread·PermaLink Source updated for VS7 ralfoide 12:42 30 Sep '03   Hi! I updated the source for use with VS7/.Net and saved an archive here: http://www.beatware.com/~ralf/CRegistry_VS7_RM20030930.zip Modifications: - Unicode and MBCS (using LPTSTR and TCHAR) - GetValue string using a allocated buffer of the right size freed after - No more warning or errors with VS7 I'll probably remove the RegFlushKey too later, btw. Enjoy R/ Sign In·View Thread·PermaLink 3.00/5 (1 vote) Should RegFlushKey be used? Baz 5:53 18 Jul '03   Hi there Carlos! Great job on the creation of another great MFC/C++ class! Anyway, should you be using the RegFlushKey() function as the MSDN states: "An application should only call RegFlushKey if it requires absolute certainty that registry changes are on disk. In general, RegFlushKey rarely, if ever, need be used." because.... (it says earlier in the article)... "It is not necessary to call RegFlushKey to change a key. Registry changes are flushed to disk by the registry using its lazy flusher" I tend to stick to what Microsods say cos if they mention something, I tend to think of it as an admittance of a bug (me being cynical?! )What's your ideas on that? Sign In·View Thread·PermaLink 1.33/5 (3 votes) VC7 compiler errors/warnings C++ Hacker 4:17 23 Jan '03   Hello, I get the following errors compiling with VC7: Compiling... Registry.cpp e:\temp\BugRTCsu\Registry.h(28) : error C2058: constant expression is not integral e:\temp\BugRTCsu\Registry.h(29) : error C2058: constant expression is not integral e:\temp\BugRTCsu\Registry.h(30) : error C2058: constant expression is not integral e:\temp\BugRTCsu\Registry.h(31) : error C2058: constant expression is not integral e:\temp\BugRTCsu\Registry.h(32) : error C2058: constant expression is not integral e:\temp\BugRTCsu\Registry.h(33) : error C2058: constant expression is not integral e:\temp\BugRTCsu\Registry.h(35) : error C2058: constant expression is not integral If I cast the keys to (int) I get the following warnings Registry.h(28) : warning C4311: 'type cast' : pointer truncation from 'HKEY' to 'int' Registry.h(29) : warning C4311: 'type cast' : pointer truncation from 'HKEY' to 'int' Registry.h(30) : warning C4311: 'type cast' : pointer truncation from 'HKEY' to 'int' Registry.h(31) : warning C4311: 'type cast' : pointer truncation from 'HKEY' to 'int' Registry.h(32) : warning C4311: 'type cast' : pointer truncation from 'HKEY' to 'int' Registry.h(33) : warning C4311: 'type cast' : pointer truncation from 'HKEY' to 'int' Registry.h(35) : warning C4311: 'type cast' : pointer truncation from 'HKEY' to 'int' You can resolve this problem by deleting the enum Keys and changing all parameters of the member functions from enum Keys to HKEY. warnings (switch /Wp64 set): Registry.cpp(47) : warning C4267: 'argument' : conversion from 'size_t' to 'DWORD', possible loss of data Registry.cpp(113) : warning C4311: 'type cast' : pointer truncation from 'DWORD *__w64 ' to 'DWORD' Can you please resolve this problem, thanks a lot, Andreas. Sign In·View Thread·PermaLink 1.25/5 (4 votes) EnumKey Michael Ehehalt 20:41 8 Dec '02   What do you mean about new functionality EnumKey? Code of function EnumKey: BOOL EnumKey(DWORD index, LPTSTR lpKey) { BOOL bRet = FALSE; DWORD lenKey; LPSTR lpstrValue; lpstrValue = (LPSTR)malloc(sizeof(char) * 256); memset(lpstrValue, 0, sizeof(char) * 256); if(::RegEnumKeyEx((HKEY)m_hKey, index, lpstrValue, &lenKey, 0, NULL, NULL, NULL) == ERROR_SUCCESS) { strcpy(lpKey, lpstrValue); bRet = TRUE; } else { strcpy(lpKey, ""); } return bRet; } The Keys can get in a loop like this: DWORD index = 0; LPTSTR lpKey=new char[256]; while(EnumKey(index, lpKey)) { ... index++; } Bye Sign In·View Thread·PermaLink 2.00/5 (1 vote) Re: EnumKey Bruno Scopinho 13:31 4 Jan '07   Very nice code Michael Ehehalt. Thanks! Sign In·View Thread·PermaLink bug in GetValue Michael Ehehalt 20:31 8 Dec '02   In GetValue the lpcbData (msdn: Pointer to a variable that specifies the size, in bytes) is set to 1024, but the length of the read string is only 256 - both hardcoded! So if the string in the registry is bigger than 256 the program crashes ... Sign In·View Thread·PermaLink bug in the readstring Thomas George 15:08 1 Oct '02   You can get the length of the string and allocate space rather than hardcoding a 256 byte buffer. Sign In·View Thread·PermaLink 2.00/5 (1 vote) Problem with Hkey local machine Zvika Vered 7:11 18 Aug '02   :(The class returns FALSE if the user is not administrator and tries to open a key and get values in HKEY_LOCAL_MACHINE. The key is in: \software\ELTA\MyApp Sign In·View Thread·PermaLink 2.00/5 (1 vote) Re: Problem with Hkey local machine Raimon81 3:34 4 Nov '05   Even I have a administrator rigts, that I can't remove some keys from HKEY_LOCAL_MACHINE. When I try that with regedit application, befor I am able to remove a key I must change a permission to them (right mouse click on key and permissions). After I set all permission to my group I am able to remove register entries. My question is how can I change permission to the key from Windows API? That is needed if I want to remove keys from HKEY_LOCAL_MACHINE. Janusz Sign In·View Thread·PermaLink 2.00/5 (1 vote) Problem with .Net! George Clarence 0:12 7 Aug '02   Hi! I have used your very usefull class within my Project in VC++ 6.0 and it has worked properly. Now, I have upgraded to .Net and I have recompiled my Project, but I have recieved several errors, like this one: error C2058: constant expression is not integral The errors are with these lines: classesRoot = HKEY_CLASSES_ROOT, classesRoot = HKEY_CLASSES_ROOT, currentUser = HKEY_CURRENT_USER, localMachine = HKEY_LOCAL_MACHINE, currentConfig = HKEY_CURRENT_CONFIG, users = HKEY_USERS, performanceData = HKEY_PERFORMANCE_DATA, etc... Can you help me please? Best regards -George Clarence Sign In·View Thread·PermaLink Re: Problem with .Net! Carlos Antollini 4:47 7 Aug '02   George, I have not the .Net in my Office, but when I stay at home I will test my class, and will make the necesary changes, for the class works in .Net.... Cheers!!! Carlos Antollini. Sonork ID 100.10529 cantollini Sign In·View Thread·PermaLink Re: Problem with .Net! George Clarence 5:32 7 Aug '02   Dear Carlos, thank you very much for your message. I have resolved this problem by adding (int) in front of the key names. I still have other problems with my project. The warning level is 3, is it too high? Why I recieve so many strange errors? Best regards George Sign In·View Thread·PermaLink Rename key ZhangFei 7:19 3 Aug '02   anyone know how to rename a key programmatically? I cann't a function call to rename registry key name. Thanks Sign In·View Thread·PermaLink 2.00/5 (2 votes) Sub-key delete Anonymous 23:36 16 Jul '02   Great class. Very minor suggestion is that you can use the DeleteKey to delete a key and all its sub-keys on Win9x, but it doesnt work the same on WinNT/2000. If you replace the RegDeleteKey with SHDeleteKey then it works the same on all systems! (you'll need IE 4, and link with shlwapi.dll) Sign In·View Thread·PermaLink

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