RegQueryValueEx

[ipe]

Hi all!
I'm looking for the easiest way to read some registry key but i am really newbie.
i search in msdn and inside this forum but everything i found is too complex and i couldn't understand. Someone could help me to call this windows api plz!? I just want to store some registry key value into a variable.

thanks for any help

[anonytmouse]

A couple of helper functions that I use:

// =====================================================================================
HRESULT RegGetString(HKEY hKey, LPCTSTR szValueName, LPTSTR * lpszResult) {

	// Given a HKEY and value name returns a string from the registry.
	// Upon successful return the string should be freed using free()
	// eg. RegGetString(hKey, TEXT("my value"), &szString);

	DWORD dwType=0, dwDataSize=0, dwBufSize=0;
	LONG lResult;

	// Incase we fail set the return string to null...
	if (lpszResult != NULL) *lpszResult = NULL;

	// Check input parameters...
	if (hKey == NULL || lpszResult == NULL) return E_INVALIDARG;

	// Get the length of the string in bytes (placed in dwDataSize)...
	lResult = RegQueryValueEx(hKey, szValueName, 0, &dwType, NULL, &dwDataSize );

	// Check result and make sure the registry value is a string(REG_SZ)...
	if (lResult != ERROR_SUCCESS) return HRESULT_FROM_WIN32(lResult);
	else if (dwType != REG_SZ)    return DISP_E_TYPEMISMATCH;

	// Allocate memory for string - We add space for a null terminating character...
	dwBufSize = dwDataSize + (1 * sizeof(TCHAR));
	*lpszResult = malloc(dwBufSize);

	if (*lpszResult == NULL) return E_OUTOFMEMORY;

	// Now get the actual string from the registry...
	lResult = RegQueryValueEx(hKey, szValueName, 0, &dwType, (LPBYTE) *lpszResult, &dwDataSize );

	// Check result and type again.
	// If we fail here we must free the memory we allocated...
	if (lResult != ERROR_SUCCESS) { free(*lpszResult); return HRESULT_FROM_WIN32(lResult); }
	else if (dwType != REG_SZ)    { free(*lpszResult); return DISP_E_TYPEMISMATCH; }

	// We are not guaranteed a null terminated string from RegQueryValueEx.
	// Explicitly null terminate the returned string...
	(*lpszResult)[(dwBufSize / sizeof(TCHAR)) - 1] = TEXT('\0');

	return NOERROR;
}


// =====================================================================================
HRESULT RegGetDWord(HKEY hKey, LPCTSTR szValueName, DWORD * lpdwResult) {

	// Given a value name and an hKey returns a DWORD from the registry.
	// eg. RegGetDWord(hKey, TEXT("my dword"), &dwMyValue);

	LONG lResult;
	DWORD dwDataSize = sizeof(DWORD);
	DWORD dwType = 0;

	// Check input parameters...
	if (hKey == NULL || lpdwResult == NULL) return E_INVALIDARG;

	// Get dword value from the registry...
	lResult = RegQueryValueEx(hKey, szValueName, 0, &dwType, (LPBYTE) lpdwResult, &dwDataSize );

	// Check result and make sure the registry value is a DWORD(REG_DWORD)...
	if (lResult != ERROR_SUCCESS) return HRESULT_FROM_WIN32(lResult);
	else if (dwType != REG_DWORD) return DISP_E_TYPEMISMATCH;

	return NOERROR;
}

Usage:

	HKEY hKey         = NULL;
	LONG lResult;
	LPTSTR szVal;
	DWORD dwVal;

	// Open the registry key...
	lResult = RegOpenKeyEx(HKEY_LOCAL_MACHINE, "SOFTWARE\\Company\\Program", 0, KEY_QUERY_VALUE, &hKey);

	if (lResult != ERROR_SUCCESS) return;

	// Get the registry values...
	hr = RegGetString(hKey, TEXT("szVal"), &szVal);
	if (FAILED(hr)) return;

	hr = RegGetDWord(hKey,  TEXT("dwVal"), &dwVal);
	if (FAILED(hr)) return;

	// Print the results...
	printf("The values: %s, %d", szVal, dwVal);

[ipe]

thank you! it helped a lot