Error checking

[links]

I'm having trouble understanding the following piece of code:

if (!RegisterClass (&wndclass))
{
    MessageBox (NULL, TEXT ("This program requires Windows NT!"),
    szAppName, MB_ICONERROR) ;
    return 0 ;
} 

If I'm correct this is C-style error checking?
Would a C++ programmer use an exception here? How would that look?
Will someone please be so kind to explain this code to me? I understand an if (x != 0) check, but I don't understand the !Function check in the code above.

Thanks in advance.