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Registry Class

By , 17 Nov 1999
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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

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

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

 
QuestionIs there any license limitation ? PinmemberMember 449889214-Jun-09 22:46 
GeneralQuerySubKeys PinmemberVider1-Aug-07 2:31 
Dear Robert, first thank's very much for share your code, nice Job,
 
I start to use it, and I need another functionaly, navigate trough subkeys, I add this fuctionaly to your class and I thing it's a good function to include in the article,
 

BOOL CRegistry::QuerySubKey(int index, CString& subkeyname)
{
TCHAR achKey[MAX_KEY_LENGTH]; // buffer for subkey name
DWORD cbName; // size of name string
TCHAR achClass[MAX_PATH] = TEXT(""); // buffer for class name
DWORD cchClassName = MAX_PATH; // size of class string
DWORD cSubKeys=0; // number of subkeys
DWORD cbMaxSubKey; // longest subkey size
DWORD cchMaxClass; // longest class string
DWORD cValues; // number of values for key
DWORD cchMaxValue; // longest value name
DWORD cbMaxValueData; // longest value data
DWORD cbSecurityDescriptor; // size of security descriptor
FILETIME ftLastWriteTime; // last write time
 
DWORD i, retCode;
 
HKEY hKey;
ASSERT(m_strCurrentPath.GetLength() > 0);
 
if (::RegOpenKeyEx(m_hRootKey, LPCTSTR(m_strCurrentPath), 0,
KEY_ALL_ACCESS, &hKey) != ERROR_SUCCESS) return FALSE;
 
TCHAR achValue[MAX_VALUE_NAME];
DWORD cchValue = MAX_VALUE_NAME;
 
// Get the class name and the value count.
retCode = RegQueryInfoKey(
hKey, // key handle
achClass, // buffer for class name
&cchClassName, // size of class string
NULL, // reserved
&cSubKeys, // number of subkeys
&cbMaxSubKey, // longest subkey size
&cchMaxClass, // longest class string
&cValues, // number of values for this key
&cchMaxValue, // longest value name
&cbMaxValueData, // longest value data
&cbSecurityDescriptor, // security descriptor
&ftLastWriteTime); // last write time
 
// Enumerate the subkeys, until RegEnumKeyEx fails.
 
if (cSubKeys)
{
if ((index < 0) || (index >= cSubKeys))
return FALSE;
 
cbName = MAX_KEY_LENGTH;
retCode = RegEnumKeyEx(hKey, index,
achKey,
&cbName,
NULL,
NULL,
NULL,
&ftLastWriteTime);
if (retCode == ERROR_SUCCESS)
{
subkeyname = achKey;
}
else
return FALSE;
}
 
::RegCloseKey(hKey);
 
return TRUE;
}

 
And a little example of how to use it:
 

m_reg.SetRootKey(HKEY_LOCAL_MACHINE);
if (m_reg.SetKey("Software\\NFFormDestiller\\ExportDrivers", FALSE)) {
for (int x = 0; x < m_reg.GetSubKeyCount(); x++) {
CString subkey;
if (m_reg.QuerySubKey(x, subkey)) {
CRegistry reg;
reg.SetRootKey(HKEY_LOCAL_MACHINE);
if (reg.SetKey("Software\\NFFormDestiller\\ExportDrivers\\"+subkey, FALSE)) {
CString desc = reg.ReadString("","");
int index = m_lstcfg.InsertItem(x,desc,0);
m_lstcfg.SetItemText(index,1,subkey);
}
}
}
}

 
Best Regards
Rey
GeneralRe: QuerySubKeys Pinmemberkid_sputnik7-Oct-07 5:27 
GeneralRegistry problem when UNICODE is defined Pinmemberrajan40083-Aug-06 5:09 
AnswerRe: Registry problem when UNICODE is defined Pinmemberchsml7-Oct-06 9:50 
GeneralRegnum buffer PinmemberJRaiden31-Jul-06 0:40 
NewsNT Native Registry API version of this here! PinmemberDan Madden19-Jun-06 18:29 
GeneralRead type Binary PinmemberDRLaverdure16-May-06 7:37 
NewsRe: Read type Binary PinmemberDan Madden19-Jun-06 18:32 
GeneralWriteDword PinmemberJason Sundram16-Oct-05 19:47 
NewsRe: WriteDword PinmemberDan Madden19-Jun-06 18:39 
GeneralUNICODE bug PinmemberWarren Stevens11-Aug-05 6:17 
GeneralRe: UNICODE bug PinmembersGrabert11-Sep-07 21:26 
QuestionKEY_ALL_ACCESS for reading ? Pinmembercross bones style23-Mar-05 3:20 
AnswerRe: KEY_ALL_ACCESS for reading ? Pinmemberkid_sputnik7-Oct-07 5:59 
GeneralRe: KEY_ALL_ACCESS for reading ? Pinmemberkid_sputnik7-Oct-07 6:15 
GeneralAnother Thanks from me! Pinmemberhazem-mk22-May-04 3:43 
GeneralExcellent PinmemberBalkrishna Talele11-May-04 21:08 
GeneralAn Excellent Piece of Code PinmemberKaren030227-Nov-03 19:31 
GeneralBugfix: Reading/writing long strings PinmemberPEK21-Jan-03 2:46 
GeneralRe: Bugfix: Reading/writing long strings PinmemberHamed Mosavi12-May-08 20:51 
GeneralKey/Value Enumeration PinmemberGermanTux22-Dec-02 2:24 
GeneralRe: Key/Value Enumeration Pinmemberlzandman24-Aug-04 2:26 
GeneralLinker warning in Release Builds Pinmemberkarl_w28-Nov-02 22:52 
GeneralRe: Linker warning in Release Builds Pinmemberkarl_w1-Dec-02 23:10 

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