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How to get the DWORD registry value on local machine?

Posted on 2009-07-09
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Last Modified: 2012-05-07
Hi, I want to retrieve the DWORD registy value in DWORD type variable. Could anyone tell me how to query directly DWORD value and stored it in DWORD type variable. I know how to retrieve string registry key. See attached code.

Thanks.
HKEY lHKeyhandle;

HKEY lhkey;

LONG lRetVal;

char* mykey;

lRetVal = RegConnectRegistry(NULL, HKEY_LOCAL_MACHINE, &lHKeyhandle);

if(lRetVal == ERROR_SUCCESS) {		

	lRetVal = RegOpenKeyEx(lHKeyhandle, "SOFTWARE\\Microsoft\\Software\\MyApp", 0, KEY_QUERY_VALUE, &lhkey);

	if(lRetVal == ERROR_SUCCESS) {  	

		LPBYTE lpData = new BYTE[_MAX_FNAME + 1];

		ZeroMemory(lpData, _MAX_FNAME + 1);

		DWORD lpcbData = _MAX_FNAME;			

                                          lRetVal = RegQueryValueExA(lhkey, TEXT("MyKey"), NULL, NULL, lpData, &lpcbData);

                                          mykey = new char[_MAX_FNAME];

		if(lRetVal == ERROR_SUCCESS)

		    sprintf(mykey, "%s", lpData);		

		RegCloseKey(lhkey);

	}

	RegCloseKey(lHKeyhandle);

}

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Question by:deshaw
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6 Comments
 
LVL 40

Assisted Solution

by:evilrix
evilrix earned 150 total points
ID: 24816417
http://msdn.microsoft.com/en-us/library/ms724868(VS.85).aspx

LONG WINAPI RegGetValue(
  __in         HKEY hkey,
  __in_opt     LPCTSTR lpSubKey,
  __in_opt     LPCTSTR lpValue,
  __in_opt     DWORD dwFlags,
  __out_opt    LPDWORD pdwType,
  __out_opt    PVOID pvData, //<-------------  &dwData
  __inout_opt  LPDWORD pcbData
);

Pass pvData as the address of a DWORD variable
0
 
LVL 86

Accepted Solution

by:
jkr earned 350 total points
ID: 24817087
Or, in your code:
HKEY lHKeyhandle;

HKEY lhkey;

LONG lRetVal;

char* mykey;

lRetVal = RegConnectRegistry(NULL, HKEY_LOCAL_MACHINE, &lHKeyhandle);

if(lRetVal == ERROR_SUCCESS) {          

        lRetVal = RegOpenKeyEx(lHKeyhandle, "SOFTWARE\\Microsoft\\Software\\MyApp", 0, KEY_QUERY_VALUE, &lhkey);

        if(lRetVal == ERROR_SUCCESS) {          

                DWORD dwValue;

                

                DWORD lpcbData = sizeof(DWORD);                    

                                          lRetVal = RegQueryValueExA(lhkey, TEXT("MyKey"), NULL, NULL, (LPBYTE) &dwValue, &lpcbData);

                                         

                if(lRetVal == ERROR_SUCCESS)

                    sprintf(mykey, "%d", dwValue);               

                RegCloseKey(lhkey);

        }

        RegCloseKey(lHKeyhandle);

}

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Author Comment

by:deshaw
ID: 24817155
Thanks both of you. The posts were helpful. My solution is below and working fine. Let me know if you think there is any amiss.
HKEY lhkey;
LONG lRetVal;
DWORD dwType, dwSize;
//set default value
DWORD mykey= 0;

try {
     if(RegOpenKeyEx(HKEY_LOCAL_MACHINE, "SOFTWARE\\MyApp", 0, KEY_QUERY_VALUE, &lhkey) == ERROR_SUCCESS) {
    dwType = REG_DWORD;
    dwSize = sizeof(DWORD);
    RegQueryValueEx(lhkey, TEXT("myRegKey"), NULL, &dwType, (PBYTE)&mykey, &dwSize);
    RegCloseKey(lhkey);
    }
} catch(...) {
//ignore and take default value
}
Thanks.
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LVL 86

Assisted Solution

by:jkr
jkr earned 350 total points
ID: 24817246
You can omit try/catch here, since no C++ exceptions are going to be thrown. SEH might be more appropriate, e.g.
__try {

     if(RegOpenKeyEx(HKEY_LOCAL_MACHINE, "SOFTWARE\\MyApp", 0, KEY_QUERY_VALUE, &lhkey) == ERROR_SUCCESS) {

    dwType = REG_DWORD;

    dwSize = sizeof(DWORD);

    RegQueryValueEx(lhkey, TEXT("myRegKey"), NULL, &dwType, (PBYTE)&mykey, &dwSize);

    RegCloseKey(lhkey);

    }

} __except(1) {

//ignore and take default value

} 

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Author Comment

by:deshaw
ID: 24821002
ohh..great..thanks jkr...
0
 
LVL 1

Author Closing Comment

by:deshaw
ID: 31601724
Thanks...
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