libstdc++/9424: i/ostream::operator>>/<<(streambuf*) drops characters

[Nathan Myers]

The following reply was made to PR libstdc++/9424; it has been noted by GNATS.

From: Nathan Myers <ncm@cantrip.org>
To: libstdc++@gcc.gnu.org
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: libstdc++/9424: i/ostream::operator>>/<<(streambuf*) drops characters
Date: Fri, 7 Mar 2003 11:50:55 -0800

 On Wed, Feb 26, 2003 at 09:27:32AM -0000, P?tur Run?lfsson wrote:
 > I believe the relevant quote is in 27.6.2.5.3 p7, bullet 2:
 > 
 >   inserting in the output sequence fails (in which case the
 >   character to be inserted is not extracted);
 > 
 > So correct code is "as if":
 > 
 > int_type c = sbin->sgetc();
 > while (c != traits_type::eof())
 > {
 >   if (sbout->sputc(c) == traits_type::eof())
 >     break;
 >   c = sbin->snextc();
 > }
 > 
 > Of course, it should be OK to call sgetn if the function *knows*
 > that sputc won't fail (for example if epptr() - pptr() is big
 > enough).
 
 I wonder if this wouldn't be better implemented using sbumpc:
 
 > int_type c;
 > while ((c = sbin->sbumpc()) != traits_type::eof() &&
 >        (sbout->sputc(c) != traits_type::eof())
 >   {}
 
 I seem to recall that sbumpc() can be implemented more efficiently
 than snextc, although it's just possible I was smoking crack.
 
 Nathan Myers
 ncm-nospam@cantrip.org