john wrote:
> In TC++PL3, in 21.3.3, the following definition of ios_base is provided:
>
> class ios_base{
> public:
> // ...
>
> typedef implementation_defined2 iostate;
> static const iostate badbit, // stream is corrupted
> eofbit, // end-of-file seen
> failbit, // next operation will fail
> ==> goodbit; // goodbit==0
>
> // ...
> };
>
>
> What does "goodbit==0" exactly mean?

Means literally that everything is ok. 'goodbit' has no bits set and therefore
means that the IO state is not in error.