Question: Is it recommed to put a while loop, which never ends in a constructor? Or should I use threads to get the same result?
Is it good when a constructor never terminates? Or is it more secure to avoid segmentation faults?

Hope you understand my bad English..

Answer: 
An object does not exist if its constructor does not finish. So putting a while(1) loop in a constructor will prevent objects being created using that constructor. You need to describe what problem you think doing this will solve.
I'd say it's perfectly OK to spawn a thread from a constructor, and a horribly bad idea to have an endless loop in the constructor.

In code, the following is OK:

```
void start_a_thread_with_a_loop()
{
    while(1)
    {
         // consider a while(!stop_condition) or something
         // do something in a loop
    }
}

class x
{
public:
    x()
    {
        start_a_thread_with_a_loop();
    }
};

```

And the following would be at least a bad idea:

```
class x
{
public:
    x()
    {
        while(1)
        {
        }
    }
};

```

Good thing though, is that likely you wouldn't be able to use such object, for reasons Neil pointed out :)