C / C++ / MFC

  // Create a HDEVINFO with all present devices.
    hDevInfo = SetupDiGetClassDevs((LPGUID)&GUID_CLASS_USB_DEVICE,
        0, 0, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);
    
    if (hDevInfo == INVALID_HANDLE_VALUE)
 		return false;
     
 	// Enumerate through all devices in Set.
    DeviceInfoData.cbSize = sizeof(SP_DEVINFO_DATA);
    for (i = 0 ; SetupDiEnumDeviceInfo(hDevInfo, i, &DeviceInfoData) ; i++)
    {
        DWORD DataT;
        LPTSTR buffer = new char[1024];//NULL;
        DWORD buffersize = 1024;//0;
        
        // Call function with null to begin with, 
        // then use the returned buffer size 
        // to Alloc the buffer. Keep calling until
        // success or an unknown failure.
        while (!SetupDiGetDeviceRegistryProperty(hDevInfo, &DeviceInfoData,
				SPDRP_HARDWAREID, &DataT, (PBYTE)buffer, buffersize, &buffersize))
        {
            if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)
            {
                // Change the buffer size.
                if (buffer) 
					LocalFree(buffer);
                buffer = (char*)LocalAlloc(LPTR,buffersize);
            }
            else
                break;
        }
...

class MyClass<br />
{<br />
public:<br />
MyClass(); // constructor<br />
int MyMethod(int MyVariable);<br />
};

int i = 5;<br />
MyClass MyObject;<br />
MyObject.MyMethod(i);

int i = 5;<br />
MyClass().MyMethod(i);