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From: peturr02@ru.is To: gcc-gnats@gcc.gnu.org Subject: libstdc++/9661: cin.rdbuf()->sputbackc() does not put characters back to stdin Date: Tue, 11 Feb 2003 12:56:00 -0000 [thread overview] Message-ID: <20030211124802.19144.qmail@sources.redhat.com> (raw) >Number: 9661 >Category: libstdc++ >Synopsis: cin.rdbuf()->sputbackc() does not put characters back to stdin >Confidential: no >Severity: serious >Priority: medium >Responsible: unassigned >State: open >Class: sw-bug >Submitter-Id: net >Arrival-Date: Tue Feb 11 12:56:00 UTC 2003 >Closed-Date: >Last-Modified: >Originator: peturr02@ru.is >Release: gcc-3.2.1 >Organization: >Environment: Red Hat Linux 8.0 >Description: According to this posting to comp.lang.c++.moderated by Matt Austern: fxtk8ha83sv.fsf@isolde.engr.sgi.com cin.rdbuf()->sputbackc(c) and ungetc(c, stdin) should be equivalent and interchangable. Although this is a QoI issue, it seems logical to fix this since * cin.rdbuf()->sbumpc() and fgetc(stdin) are equivalent; * characters returned by cin.rdbuf()->sgetc() can be consumed by both cin.rdbuf()->sbumpc() and fgetc(stdin) * characters put back by ungetc will be returned by cin; that is, cin.rdbuf()->sputbackc is the only case where the effect on cin and stdin differs. >How-To-Repeat: See attachment. >Fix: >Release-Note: >Audit-Trail: >Unformatted: ----gnatsweb-attachment---- Content-Type: text/plain; name="stdiosync.cc" Content-Disposition: inline; filename="stdiosync.cc" #include <cstdio> #include <iostream> #undef NDEBUG #include <cassert> int main() { using namespace std; int c1 = fgetc(stdin); int c2 = cin.rdbuf()->sputbackc(c1); assert(c2 == c1); int c3 = fgetc(stdin); assert(c3 == c1); ungetc(c3, stdin); int c4 = cin.rdbuf()->sgetc(); assert(c4 == c3); return 0; }
next reply other threads:[~2003-02-11 12:56 UTC|newest] Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top 2003-02-11 12:56 peturr02 [this message] 2003-05-16 20:00 bkoz
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