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libstdc++/8636: global ostringstreams lose their data
- From: michael dot pronath at gmx dot de
- To: gcc-gnats at gcc dot gnu dot org
- Date: 19 Nov 2002 13:44:46 -0000
- Subject: libstdc++/8636: global ostringstreams lose their data
- Reply-to: michael dot pronath at gmx dot de
>Number: 8636
>Category: libstdc++
>Synopsis: global ostringstreams lose their data
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Tue Nov 19 05:46:05 PST 2002
>Closed-Date:
>Last-Modified:
>Originator: michael.pronath@gmx.de
>Release: unknown-1.0
>Organization:
>Environment:
Linux glibc2 g++ 3.2
both in debian package and when compiled from source
>Description:
global ostringstreams lose their data after calling
c_str on them when new memory is allocated.
See appended example.
Expected output: Hello World, where are you?
real output: Hello Hello Hello Hello Hell
reason: when fillmystream() returns, the ostringstream content is forgotten, just like it was an automatic
variable. The string operator+= then allocates new memory
for extension of the string and gets the address of x and
then appends itself.
Interestingly, this does not happen in valgrind.
>How-To-Repeat:
g++ -o teststream teststream.cc
./teststream
valgrind ./teststream
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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