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Registry Class

, 17 Nov 1999
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A simple registry class
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OK, there are many registry classes out there, but this is the one I wrote. I have used it for years in many commercial applications, so it is quite well tested in terms of reading and writing values. The only weakness of the class is that it does not have extensive support for deleting or copying keys.

There are a few useful features in the class worth noting:

  • When reading a value, you can provide a default value in case the operation fails.
  • You can read and write objects such as CFonts, CPoints, etc. from/to the registry.

How to Use the Class

  1. Declare a CRegistry object local to your function.
  2. Call CRegistry::SetRootKey(HKEY hRootKey) to set the root key.
  3. Call CRegistry::SetKey(CString strKey, BOOL bCanCreate). Pass bCanCreate=TRUE to write to the registry. Pass bCanCreate=FALSE to read from the registry.

Here is an example...

void CMyApp::ReadRegistry()
{
	CRegistry Reg();
	Reg.SetRootKey(HKEY_LOCAL_MACHINE);
	if (Reg.SetKey("Software\\MyApp\\Settings", FALSE))
	{
		m_nData = Reg.ReadInt("Data1", 0);
		pi = Reg.ReadFloat("Pi", 3.14159);
		m_strUserName = Reg.ReadString("UserName", "Default User Name");
		Reg.ReadFont(&m_font);
	}
	else
	{
		TRACE("Failed to open key\n");
	}

}

It's just that simple!

I have included the class interface below to illustrate the variety of member functions.

#ifndef __REGISTRY_H__
#define __REGISTRY_H__

class CRegistry
{
public:
	CRegistry();
	~CRegistry();

int m_nLastError;

// CRegistry properties	
protected:
	HKEY m_hRootKey;
	BOOL m_bLazyWrite;
	CString m_strCurrentPath;

public:
	inline BOOL PathIsValid() {
		return (m_strCurrentPath.GetLength() > 0); }
	inline CString GetCurrentPath() {
		return m_strCurrentPath; }
	inline HKEY GetRootKey() {
		return m_hRootKey; }


//CRegistry	methods
public:
	BOOL ClearKey();
	BOOL SetRootKey(HKEY hRootKey);
	BOOL CreateKey(CString strKey);
	BOOL DeleteKey(CString strKey);
	BOOL DeleteValue(CString strName);
	int GetDataSize(CString strValueName);
	DWORD GetDataType(CString strValueName);
	int GetSubKeyCount();
	int GetValueCount();
	BOOL KeyExists(CString strKey, HKEY hRootKey = NULL);
	BOOL SetKey(CString strKey, BOOL bCanCreate);
	BOOL ValueExists(CString strName);
	void RenameValue(CString strOldName, CString strNewName);

	// data reading functions
	COleDateTime ReadDateTime(CString strName, COleDateTime dtDefault);
	double ReadFloat(CString strName, double fDefault);
	CString ReadString(CString strName, CString strDefault);
	int ReadInt(CString strName, int nDefault);
	BOOL ReadBool(CString strName, BOOL bDefault);
	COLORREF ReadColor(CString strName, COLORREF rgbDefault);
	BOOL ReadFont(CString strName, CFont* pFont);
	BOOL ReadPoint(CString strName, CPoint* pPoint);
	BOOL ReadSize(CString strName, CSize* pSize);
	BOOL ReadRect(CString strName, CRect* pRect);
	DWORD ReadDword(CString strName, DWORD dwDefault);

	// data writing functions
	BOOL WriteBool(CString strName, BOOL bValue);
	BOOL WriteDateTime(CString strName, COleDateTime dtValue);
	BOOL WriteString(CString strName, CString strValue);
	BOOL WriteFloat(CString strName, double fValue);
	BOOL WriteInt(CString strName, int nValue);
	BOOL WriteColor(CString strName, COLORREF rgbValue);
	BOOL WriteFont(CString strName, CFont* pFont);
	BOOL WritePoint(CString strName, CPoint* pPoint);
	BOOL WriteSize(CString strName, CSize* pSize);
	BOOL WriteRect(CString strName, CRect* pRect);
	BOOL WriteDword(CString strName, DWORD dwValue);

};// end of CRegistry class definition


#endif

License

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About the Author

Robert Pittenger, MCPD-EAD
President Starpoint Software Inc.
United States United States
Bob Pittenger is founder and President of Starpoint Software Inc. He holds a B.A. degree from Miami University, M.S. and Ph.D. degrees from Purdue University, and an MBA from Xavier University. He has been programming since 1993, starting with Windows application development in C++/MFC and moving to C# and .NET around 2005 and is a .NET Microsoft Certified Professional Developer.

Bob is the author of two books:
Billionaire: How the Ultra-Rich Built Their Fortunes Through Good and Evil and What You Can Learn from Them
and
Wealthonomics: The Most Important Economic and Financial Concepts that Can Make You Rich Fast.
Visit http://www.billionairebook.net for more information.

Comments and Discussions

 
QuestionWriteString Unicode Pin
dimag at 18-Jun-14 8:11
memberdimag18-Jun-14 8:11 
QuestionIs there any license limitation ? Pin
Member 4498892 at 14-Jun-09 23:46
memberMember 449889214-Jun-09 23:46 
GeneralQuerySubKeys Pin
Vider at 1-Aug-07 3:31
memberVider1-Aug-07 3:31 
GeneralRe: QuerySubKeys Pin
kid_sputnik at 7-Oct-07 6:27
memberkid_sputnik7-Oct-07 6:27 
GeneralRegistry problem when UNICODE is defined Pin
rajan4008 at 3-Aug-06 6:09
memberrajan40083-Aug-06 6:09 
AnswerRe: Registry problem when UNICODE is defined Pin
chsml at 7-Oct-06 10:50
memberchsml7-Oct-06 10:50 
GeneralRegnum buffer Pin
JRaiden at 31-Jul-06 1:40
memberJRaiden31-Jul-06 1:40 
NewsNT Native Registry API version of this here! Pin
Dan Madden at 19-Jun-06 19:29
memberDan Madden19-Jun-06 19:29 
GeneralRead type Binary Pin
DRLaverdure at 16-May-06 8:37
memberDRLaverdure16-May-06 8:37 
NewsRe: Read type Binary Pin
Dan Madden at 19-Jun-06 19:32
memberDan Madden19-Jun-06 19:32 
GeneralWriteDword Pin
Jason Sundram at 16-Oct-05 20:47
memberJason Sundram16-Oct-05 20:47 
NewsRe: WriteDword Pin
Dan Madden at 19-Jun-06 19:39
memberDan Madden19-Jun-06 19:39 
GeneralUNICODE bug Pin
Warren Stevens at 11-Aug-05 7:17
memberWarren Stevens11-Aug-05 7:17 
GeneralRe: UNICODE bug Pin
sGrabert at 11-Sep-07 22:26
membersGrabert11-Sep-07 22:26 
QuestionKEY_ALL_ACCESS for reading ? Pin
cross bones style at 23-Mar-05 4:20
membercross bones style23-Mar-05 4:20 
I've noted that if you are a non-priviliged user and you want to read the Registry, you may encounter problem when you use CRegistry::KeyExists and CRegistry::SetKey.

This seems due to the fact that these methods call ::RegOpenKeyEx with KEY_ALL_ACCESS parameter. I've seen that if you use KEY_READ everything is ok.

I'm not familiar with Microsoft security access masks, MSDN says that KEY_ALL_ACCESS is a combination of KEY_READ, KEY_WRITE and KEY_CREATE_LINK but it is not clear whether the combination is AND or OR.
From this, it seems to me that KEY_ALL_ACCESS requires both read and write rights, the latter not being available to a non-priviliged user.

So, why KEY_ALL_ACCESS has been used for reading ? Isn't KEY_READ more appropriate ?
AnswerRe: KEY_ALL_ACCESS for reading ? Pin
kid_sputnik at 7-Oct-07 6:59
memberkid_sputnik7-Oct-07 6:59 
GeneralRe: KEY_ALL_ACCESS for reading ? Pin
kid_sputnik at 7-Oct-07 7:15
memberkid_sputnik7-Oct-07 7:15 
GeneralAnother Thanks from me! Pin
hazem-mk at 22-May-04 4:43
memberhazem-mk22-May-04 4:43 
GeneralExcellent Pin
Balkrishna Talele at 11-May-04 22:08
memberBalkrishna Talele11-May-04 22:08 
GeneralAn Excellent Piece of Code Pin
Karen0302 at 27-Nov-03 20:31
memberKaren030227-Nov-03 20:31 
GeneralBugfix: Reading/writing long strings Pin
PEK at 21-Jan-03 3:46
memberPEK21-Jan-03 3:46 
GeneralRe: Bugfix: Reading/writing long strings Pin
Hamed Mosavi at 12-May-08 21:51
memberHamed Mosavi12-May-08 21:51 
GeneralKey/Value Enumeration Pin
GermanTux at 22-Dec-02 3:24
memberGermanTux22-Dec-02 3:24 
GeneralRe: Key/Value Enumeration Pin
lzandman at 24-Aug-04 3:26
memberlzandman24-Aug-04 3:26 
GeneralLinker warning in Release Builds Pin
karl_w at 28-Nov-02 23:52
memberkarl_w28-Nov-02 23:52 

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Article Copyright 1999 by Robert Pittenger, MCPD-EAD
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