Here's a solution, too:
int main()
{
QUuid uuid;
while ( (uuid = QUuid::createUuid()) != QUuid::createUuid() ) { }
std::cout << "Aha! I've found one! " << qPrintable( uuid.toString() ) << std::endl;
}
Note: requires Qt, but I guarantee that if you let it run long enough, it might find one.
(Note note: actually, now that I'm looking at it, there may be something about the generation algorithm that prevents two subsequently generated uuids that collide--but I kinda doubt it).