Thread: Registry functions, not there?

Hello,

I'm not familiar with RegGetValue(). Though, I am familiar with RegOpenKeyEx, RegQueryValueEx, RegCloseKey, and so forth.

I did a Google search on RegGetValue, and this is what turned up: MSDN. At the bottom it says: Requires Windows Server 2003 SP1. This may answer your question.


- Stack Overflow

Hello,

Simply, parameter 5 is the address to the data of your buffer and parameter 6 is the address of data buffer size.

I don't make a habit of posting code, though I think it may be beneficial. I apologize for using printf() and other C-style functions in the C++ board. So, here is an example I wrote on how to query a registry key. It may help gear you in the right direction:

Code:

#include <windows.h>
#include <stdio.h>

int checkKey(HKEY tree, const char *folder, char *key) {
	long lRet;
	HKEY hKey;
	char temp[150];
	DWORD dwBufLen;

	// Open location
	lRet = RegOpenKeyEx( tree, folder, 0, KEY_QUERY_VALUE, &hKey );
	if (lRet != ERROR_SUCCESS)
		return 0;

	// Get key
	dwBufLen = sizeof(temp);
	lRet = RegQueryValueEx( hKey, key, NULL, NULL, (BYTE*)&temp, &dwBufLen );
	if (lRet != ERROR_SUCCESS)
		return 0;

	printf("Key value: %s\n", temp);

	// Close key
	lRet = RegCloseKey( hKey );
	if (lRet != ERROR_SUCCESS)
		return 0;

	// Got this far, then key exists
	return 1;
}

int main() {
	printf("Checking for key: HKEY_CURRENT_USER -> Control Panel -> Desktop -> Wallpaper\n");

	if (checkKey(HKEY_CURRENT_USER, "Control Panel\\Desktop", "Wallpaper"))
		printf("Key Exists.\n");
	else
		printf("Key Does Not Exist.\n");

	return 0;
}

RegQueryValueEx()
The RegQueryValueEx function retrieves the type and data for a specified value name associated with an open registry key.

Code:

LONG RegQueryValueEx(
    HKEY hKey,		// handle of key to query

    LPTSTR lpValueName,	// address of name of value to query

    LPDWORD lpReserved,	// reserved

    LPDWORD lpType,	// address of buffer for value type

    LPBYTE lpData,	// address of data buffer

    LPDWORD lpcbData	// address of data buffer size
);

Or learn more about it here.

There are other functions, though simply doing an MSDN/Google search may pull up further documentation on such functions within the windows header file.

If you have any further questions please feel free to ask.


- Stack Overflow

As a shortcut, you can use SHGetValue. Whether you use SHGetValue or RegQueryValueEx, you must make sure that a retrieved string is nul terminated before trying to use it. You should be aware that, unless documented, keys in the registry may change from one platform to another (or even when a hotfix is released).

Code:

#include <windows.h>
#include <shlwapi.h>
#include <stdio.h>
#pragma comment(lib, "shlwapi.lib")

int main(void)
{
    TCHAR szName[500];
    DWORD dwType;
    DWORD cbSize = sizeof(szName) - sizeof(TCHAR); /* Leave room for nul terminator. */

    if (SHGetValue(HKEY_LOCAL_MACHINE,
                   TEXT("HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0"),
                   TEXT("ProcessorNameString"),
                   &dwType,
                   szName,
                   &cbSize) == ERROR_SUCCESS)
    {
        /* IMPORTANT: Make sure string is nul terminated. */
        szName[cbSize / sizeof(TCHAR)] = TEXT('\0');

        printf("Name is %s.\n", szName);
    }
    else
    {
        printf("Failed to retrieve value.\n");
    }

    getchar();
    return 0;
}

>> BYTE* var;

that doesn't point to anything.

>> sizeof(var)

the parameter should be a pointer to the size of the buffer - on return it will contain the number of bytes copied.

>> I must have forgoten alot about c++, but what is wrong?

ever heard of documentation? it's a nice thing to have when you can't remember function parameters. here's borland's WinAPI help file: download.