cin/streambuf-problem

[R. Sinoradzki]

Thanks for your reply.
Perhaps I understand something wrong. But the reason I wonder is that
this method is from Stroustrup, 'The C++ Programming Language' 3rd Edition.

This is what ISO-C++ 98 says.

(quote)

27.5.2.2.3 Get area [lib.streambuf.pub.get]

streamsize in_avail();
Returns: If a read position is available, returns egptr() - gptr().

....

char_type* gptr() const;
Returns: The next pointer for the input sequence. 
....
char_type* egptr() const;
Returns: The end pointer for the input sequence.

(end of quote)

I followed the program with my debugger. 
'egptr() - gptr()' is returned but the result is 1.

In my opinion it should be the number of characters that are left in the
streambuf.

I perhaps try to compile a full debug-version and watch out, what really
happens.

Regards, 
Ralf

Carlo Wood wrote:
> 
> On Fri, May 18, 2001 at 11:53:43PM +0200, R. Sinoradzki wrote:
> > I have this little program. It does not behave as
> > expected with gcc-3.0 and it's stdlib.
> > If I type for example "hello" the loop runs 5 times,
> > before the next 'cin' because 'cin.rdbuf()->in_avail()'
> > reports only 1.
> 
> >From the top my head (I am not at home right now, but telnetted
> into my PC (no GUI)), streambuf::in_avail() doesn't return the
> number of buffered characters, but only the number that can
> be read quickly (the current contiguous ammount in the get area?).
> I even seem to remember that the default implementation is currently
> to always return 1.  In other words: I might be wrong but I think you
> shouldn't use in_avail(), it means something else then you (apparently)
> think it means.
> 
> --
> Carlo Wood <carlo@alinoe.com>