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2008
<a class="ulink" href="http://www.fsf.org" target="_top">FSF</a>
- </p></div></div><hr /></div><div class="qandaset"><dl><dt>1. <a href="faq.html#faq.info">General Information</a></dt><dd><dl><dt>1.1. <a href="faq.html#faq.what">
+ </p></div></div><hr /></div><div class="qandaset"
title="Frequently Asked Questions"><a id="id460433"></a><dl><dt>1. <a href="faq.html#faq.info">General Information</a></dt><dd><dl><dt>1.1. <a href="faq.html#faq.what">
What is libstdc++?
</a></dt><dt>1.2. <a href="faq.html#faq.why">
Why should I use libstdc++?
What's an ABI and why is it so messy?
</a></dt><dt>7.8. <a href="faq.html#faq.size_equals_capacity">
How do I make std::vector<T>::capacity() == std::vector<T>::size?
- </a></dt></dl></dd></dl><table border="0"
summary="Q and A Set"><col align="left" width="1%" /><tbody><tr class="qandadiv"><td align="left" valign="top" colspan="2"><h3 class="title"><a id="faq.info"></a>1. General Information</h3></td></tr><tr class="toc"><td align="left" valign="top" colspan="2"><dl><dt>1.1. <a href="faq.html#faq.what">
+ </a></dt></dl></dd></dl><table border="0"
width="100%" summary="Q and A Set"><col align="left" width="1%" /><col /><tbody><tr class="qandadiv"><td align="left" valign="top" colspan="2"><h3 class="title"><a id="faq.info"></a>1. General Information</h3></td></tr><tr class="toc"><td align="left" valign="top" colspan="2"><dl><dt>1.1. <a href="faq.html#faq.what">
What is libstdc++?
</a></dt><dt>1.2. <a href="faq.html#faq.why">
Why should I use libstdc++?
What happened to the older libg++? I need that!
</a></dt><dt>1.7. <a href="faq.html#faq.more_questions">
What if I have more questions?
- </a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.what"></a><a id="faq.what.q"></a><p><b>1.1.</b></p></td><td align="left" valign="top"><p>
+ </a></dt></dl></td></tr><tr class="question"
title="1.1."><td align="left" valign="top"><a id="faq.what"></a><a id="faq.what.q"></a><p><b>1.1.</b></p></td><td align="left" valign="top"><p>
What is libstdc++?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="faq.what.a"></a></td><td align="left" valign="top"><p>
The GNU Standard C++ Library v3 is an ongoing project to
bleeding-edge code, the up-to-date source is available over
anonymous SVN, and can even be browsed over
the <a class="ulink" href="http://gcc.gnu.org/svn.html" target="_top">web</a>.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.why"></a><a id="q-why"></a><p><b>1.2.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="1.2."><td align="left" valign="top"><a id="faq.why"></a><a id="q-why"></a><p><b>1.2.</b></p></td><td align="left" valign="top"><p>
Why should I use libstdc++?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-why"></a></td><td align="left" valign="top"><p>
The completion of the ISO C++ standardization gave the C++
community a powerful set of reuseable tools in the form of the C++
Standard Library. However, all existing C++ implementations are
- (as the Draft Standard used to say) “<span class="quote">incomplet and
- incorrekt</span>”, and many suffer from limitations of the compilers
+ (as the Draft Standard used to say) <span class="quote">“<span class="quote">incomplet and
+ incorrekt</span>”</span>, and many suffer from limitations of the compilers
that use them.
</p><p>
The GNU compiler collection
freely available and fully compliant. (Such as
<code class="classname">string</code>,
<code class="classname">vector<></code>, iostreams, and algorithms.)
- Programmers will no longer need to “<span class="quote">roll their own</span>”
+ Programmers will no longer need to <span class="quote">“<span class="quote">roll their own</span>”</span>
nor be worried about platform-specific incompatibilities.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.who"></a><a id="q-who"></a><p><b>1.3.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="1.3."><td align="left" valign="top"><a id="faq.who"></a><a id="q-who"></a><p><b>1.3.</b></p></td><td align="left" valign="top"><p>
Who's in charge of it?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-who"></a></td><td align="left" valign="top"><p>
The libstdc++ project is contributed to by several developers
archives, is open to everyone. You can read instructions for
doing so on the <a class="ulink" href="http://gcc.gnu.org/libstdc++/" target="_top">homepage</a>.
If you have questions, ideas, code, or are just curious, sign up!
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.when"></a><a id="q-when"></a><p><b>1.4.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="1.4."><td align="left" valign="top"><a id="faq.when"></a><a id="q-when"></a><p><b>1.4.</b></p></td><td align="left" valign="top"><p>
When is libstdc++ going to be finished?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-when"></a></td><td align="left" valign="top"><p>
Nathan Myers gave the best of all possible answers, responding to
a Usenet article asking this question: <span class="emphasis"><em>Sooner, if you
help.</em></span>
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.how"></a><a id="q-how"></a><p><b>1.5.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="1.5."><td align="left" valign="top"><a id="faq.how"></a><a id="q-how"></a><p><b>1.5.</b></p></td><td align="left" valign="top"><p>
How do I contribute to the effort?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-how"></a></td><td align="left" valign="top"><p>
Here is <a class="link" href="manual/appendix_contributing.html" title="Appendix A. Contributing">a page devoted to
anybody who is willing to help write documentation, for example,
or has found a bug in code that we all thought was working and is
willing to provide details, is more than welcome!
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.whereis_old"></a><a id="q-whereis_old"></a><p><b>1.6.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="1.6."><td align="left" valign="top"><a id="faq.whereis_old"></a><a id="q-whereis_old"></a><p><b>1.6.</b></p></td><td align="left" valign="top"><p>
What happened to the older libg++? I need that!
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-whereis_old"></a></td><td align="left" valign="top"><p>
The most recent libg++ README states that libg++ is no longer
projects, and is only being kicked along to support older code.
</p><p>
More information in the <a class="link" href="manual/backwards.html" title="Backwards Compatibility">backwards compatibility documentation</a>
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.more_questions"></a><a id="q-more_questions"></a><p><b>1.7.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="1.7."><td align="left" valign="top"><a id="faq.more_questions"></a><a id="q-more_questions"></a><p><b>1.7.</b></p></td><td align="left" valign="top"><p>
What if I have more questions?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-more_questions"></a></td><td align="left" valign="top"><p>
If you have read the README file, and your question remains
How is that different from the GNU {Lesser,Library} GPL?
</a></dt><dt>2.4. <a href="faq.html#faq.license.what_restrictions">
I see. So, what restrictions are there on programs that use the library?
- </a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.license.what"></a><a id="q-license.what"></a><p><b>2.1.</b></p></td><td align="left" valign="top"><p>
+ </a></dt></dl></td></tr><tr class="question"
title="2.1."><td align="left" valign="top"><a id="faq.license.what"></a><a id="q-license.what"></a><p><b>2.1.</b></p></td><td align="left" valign="top"><p>
What are the license terms for libstdc++?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-license.what"></a></td><td align="left" valign="top"><p>
See <a class="link" href="manual/license.html" title="License">our license description</a>
for these and related questions.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.license.any_program"></a><a id="q-license.any_program"></a><p><b>2.2.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="2.2."><td align="left" valign="top"><a id="faq.license.any_program"></a><a id="q-license.any_program"></a><p><b>2.2.</b></p></td><td align="left" valign="top"><p>
So any program which uses libstdc++ falls under the GPL?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-license.any_program"></a></td><td align="left" valign="top"><p>
No. The special exception permits use of the library in
proprietary applications.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.license.lgpl"></a><a id="q-license.lgpl"></a><p><b>2.3.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="2.3."><td align="left" valign="top"><a id="faq.license.lgpl"></a><a id="q-license.lgpl"></a><p><b>2.3.</b></p></td><td align="left" valign="top"><p>
How is that different from the GNU {Lesser,Library} GPL?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-license.lgpl"></a></td><td align="left" valign="top"><p>
The LGPL requires that users be able to replace the LGPL code with a
are expanded inside the code that uses the library. So to allow people
to replace the library code, someone using the library would have to
distribute their own source, rendering the LGPL equivalent to the GPL.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.license.what_restrictions"></a><a id="q-license.what_restrictions"></a><p><b>2.4.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="2.4."><td align="left" valign="top"><a id="faq.license.what_restrictions"></a><a id="q-license.what_restrictions"></a><p><b>2.4.</b></p></td><td align="left" valign="top"><p>
I see. So, what restrictions are there on programs that use the library?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-license.what_restrictions"></a></td><td align="left" valign="top"><p>
None. We encourage such programs to be released as open source,
What's libsupc++?
</a></dt><dt>3.6. <a href="faq.html#faq.size">
This library is HUGE!
- </a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.how_to_install"></a><a id="q-how_to_install"></a><p><b>3.1.</b></p></td><td align="left" valign="top"><p>How do I install libstdc++?
+ </a></dt></dl></td></tr><tr class="question"
title="3.1."><td align="left" valign="top"><a id="faq.how_to_install"></a><a id="q-how_to_install"></a><p><b>3.1.</b></p></td><td align="left" valign="top"><p>How do I install libstdc++?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-how_to_install"></a></td><td align="left" valign="top"><p>
Often libstdc++ comes pre-installed as an integral part of many
existing Linux and Unix systems, as well as many embedded
documentation</a> for detailed
instructions. You may wish to browse those files ahead
of time to get a feel for what's required.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.how_to_get_sources"></a><a id="q-how_to_get_sources"></a><p><b>3.2.</b></p></td><td align="left" valign="top"><p>How does one get current libstdc++ sources?
+ </p></td></tr><tr class="question"
title="3.2."><td align="left" valign="top"><a id="faq.how_to_get_sources"></a><a id="q-how_to_get_sources"></a><p><b>3.2.</b></p></td><td align="left" valign="top"><p>How does one get current libstdc++ sources?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-how_to_get_sources"></a></td><td align="left" valign="top"><p>
Libstdc++ sources for all official releases can be obtained as
part of the GCC sources, available from various sites and
quality. The <a class="ulink" href="http://subversion.tigris.org" target="_top"> Subversion
home page</a> has a better description.
</p><p>
- The “<span class="quote">anonymous client checkout</span>” feature of SVN is
+ The <span class="quote">“<span class="quote">anonymous client checkout</span>”</span> feature of SVN is
similar to anonymous FTP in that it allows anyone to retrieve
the latest libstdc++ sources.
</p><p>
For more information
see <a class="ulink" href="http://gcc.gnu.org/svn.html" target="_top"><acronym class="acronym">SVN</acronym>
details</a>.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.how_to_test"></a><a id="q-how_to_test"></a><p><b>3.3.</b></p></td><td align="left" valign="top"><p>How do I know if it works?
+ </p></td></tr><tr class="question"
title="3.3."><td align="left" valign="top"><a id="faq.how_to_test"></a><a id="q-how_to_test"></a><p><b>3.3.</b></p></td><td align="left" valign="top"><p>How do I know if it works?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-how_to_test"></a></td><td align="left" valign="top"><p>
Libstdc++ comes with its own validation testsuite, which includes
conformance testing, regression testing, ABI testing, and
If you find bugs in the testsuite programs themselves, or if you
think of a new test program that should be added to the suite,
<span class="emphasis"><em>please</em></span> write up your idea and send it to the list!
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.how_to_set_paths"></a><a id="q-how_to_set_paths"></a><p><b>3.4.</b></p></td><td align="left" valign="top"><p>How do I insure that the dynamically linked library will be found?
+ </p></td></tr><tr class="question"
title="3.4."><td align="left" valign="top"><a id="faq.how_to_set_paths"></a><a id="q-how_to_set_paths"></a><p><b>3.4.</b></p></td><td align="left" valign="top"><p>How do I insure that the dynamically linked library will be found?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-how_to_set_paths"></a></td><td align="left" valign="top"><p>
Depending on your platform and library version, the error message might
be similar to one of the following:
and <span class="command"><strong>ldconfig</strong></span> for more information. The dynamic
linker has different names on different platforms but the man page
is usually called something such as <code class="filename">ld.so/rtld/dld.so</code>.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.what_is_libsupcxx"></a><a id="q-what_is_libsupcxx"></a><p><b>3.5.</b></p></td><td align="left" valign="top"><p>
+ </p><p>
+ Using LD_LIBRARY_PATH is not always the best solution, <a class="link" href="manual/using_dynamic_or_shared.html#manual.intro.using.linkage.dynamic" title="Finding Dynamic or Shared Libraries">Finding Dynamic or Shared
+ Libraries</a> in the manual gives some alternatives.
+ </p></td></tr><tr class="question" title="3.5."><td align="left" valign="top"><a id="faq.what_is_libsupcxx"></a><a id="q-what_is_libsupcxx"></a><p><b>3.5.</b></p></td><td align="left" valign="top"><p>
What's libsupc++?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-what_is_libsupcxx"></a></td><td align="left" valign="top"><p>
If the only functions from <code class="filename">libstdc++.a</code>
which you need are language support functions (those listed in
- <a class="link" href="manual/support.html" title="Part II. Support">clause 18</a> of the
+ <a class="link" href="manual/support.html" title="Chapter 4. Support">clause 18</a> of the
standard, e.g., <code class="function">new</code> and
<code class="function">delete</code>), then try linking against
<code class="filename">libsupc++.a</code>, which is a subset of
using anything from the rest of the library, such as IOStreams
or vectors, then you'll still need pieces from
<code class="filename">libstdc++.a</code>.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.size"></a><a id="q-size"></a><p><b>3.6.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="3.6."><td align="left" valign="top"><a id="faq.size"></a><a id="q-size"></a><p><b>3.6.</b></p></td><td align="left" valign="top"><p>
This library is HUGE!
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-size"></a></td><td align="left" valign="top"><p>
Usually the size of libraries on disk isn't noticeable. When a
- link editor (or simply “<span class="quote">linker</span>”) pulls things from a
+ link editor (or simply <span class="quote">“<span class="quote">linker</span>”</span>) pulls things from a
static archive library, only the necessary object files are copied
into your executable, not the entire library. Unfortunately, even
if you only need a single function or variable from an object file,
Recent GNU/Linux glibc required?
</a></dt><dt>4.8. <a href="faq.html#faq.freebsd_wchar">
Can't use wchar_t/wstring on FreeBSD
- </a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.other_compilers"></a><a id="q-other_compilers"></a><p><b>4.1.</b></p></td><td align="left" valign="top"><p>
+ </a></dt></dl></td></tr><tr class="question"
title="4.1."><td align="left" valign="top"><a id="faq.other_compilers"></a><a id="q-other_compilers"></a><p><b>4.1.</b></p></td><td align="left" valign="top"><p>
Can libstdc++ be used with non-GNU compilers?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-other_compilers"></a></td><td align="left" valign="top"><p>
Perhaps.
non-standard features of g++ that are not present in older
versions of proprietary compilers. It may take as much as a year or two
after an official release of GCC that contains these features for
- proprietary tools support these constructs.
+ proprietary tools to support these constructs.
</p><p>
In the near past, specific released versions of libstdc++ have
been known to work with versions of the EDG C++ compiler, and
vendor-specific proprietary C++ compilers such as the Intel ICC
C++ compiler.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.solaris_long_long"></a><a id="q-solaris_long_long"></a><p><b>4.2.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="4.2."><td align="left" valign="top"><a id="faq.solaris_long_long"></a><a id="q-solaris_long_long"></a><p><b>4.2.</b></p></td><td align="left" valign="top"><p>
No 'long long' type on Solaris?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-solaris_long_long"></a></td><td align="left" valign="top"><p>
By default we try to support the C99 <span class="type">long long</span> type.
commonly reported platform affected was Solaris.
</p><p>
This has been fixed for libstdc++ releases greater than 3.0.3.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.predefined"></a><a id="q-predefined"></a><p><b>4.3.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="4.3."><td align="left" valign="top"><a id="faq.predefined"></a><a id="q-predefined"></a><p><b>4.3.</b></p></td><td align="left" valign="top"><p>
<code class="constant">_XOPEN_SOURCE</code> and <code class="constant">_GNU_SOURCE</code> are always defined?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-predefined"></a></td><td align="left" valign="top"><p>On Solaris, g++ (but not gcc) always defines the preprocessor
macro <code class="constant">_XOPEN_SOURCE</code>. On GNU/Linux, the same happens
<a class="ulink" href="http://gcc.gnu.org/cgi-bin/htsearch?method=and&format=builtin-long&sort=score&words=_XOPEN_SOURCE+Solaris" target="_top">quite a bit</a>.
</p><p>This method is something of a wart. We'd like to find a cleaner
solution, but nobody yet has contributed the time.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.darwin_ctype"></a><a id="q-darwin_ctype"></a><p><b>4.4.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="4.4."><td align="left" valign="top"><a id="faq.darwin_ctype"></a><a id="q-darwin_ctype"></a><p><b>4.4.</b></p></td><td align="left" valign="top"><p>
Mac OS X <code class="filename">ctype.h</code> is broken! How can I fix it?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-darwin_ctype"></a></td><td align="left" valign="top"><p>This is a long-standing bug in the OS X support. Fortunately,
the patch is quite simple, and well-known.
<a class="ulink" href="http://gcc.gnu.org/ml/gcc/2002-03/msg00817.html" target="_top"> Here's a
link to the solution</a>.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.threads_i386"></a><a id="q-threads_i386"></a><p><b>4.5.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="4.5."><td align="left" valign="top"><a id="faq.threads_i386"></a><a id="q-threads_i386"></a><p><b>4.5.</b></p></td><td align="left" valign="top"><p>
Threading is broken on i386?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-threads_i386"></a></td><td align="left" valign="top"><p>
</p><p>Support for atomic integer operations is/was broken on i386
on an i686, then you would encounter no problems. Only when
actually running the code on a i386 will the problem appear.
</p><p>This is fixed in 3.2.2.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.atomic_mips"></a><a id="q-atomic_mips"></a><p><b>4.6.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="4.6."><td align="left" valign="top"><a id="faq.atomic_mips"></a><a id="q-atomic_mips"></a><p><b>4.6.</b></p></td><td align="left" valign="top"><p>
MIPS atomic operations
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-atomic_mips"></a></td><td align="left" valign="top"><p>
The atomic locking routines for MIPS targets requires MIPS II
</p><p>
The mips*-*-linux* port continues to use the MIPS II routines, and more
work in this area is expected.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.linux_glibc"></a><a id="q-linux_glibc"></a><p><b>4.7.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="4.7."><td align="left" valign="top"><a id="faq.linux_glibc"></a><a id="q-linux_glibc"></a><p><b>4.7.</b></p></td><td align="left" valign="top"><p>
Recent GNU/Linux glibc required?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-linux_glibc"></a></td><td align="left" valign="top"><p>When running on GNU/Linux, libstdc++ 3.2.1 (shared library version
5.0.1) and later uses localization and formatting code from the system
- C library (glibc) version 2.2.5. That version of glibc is over a
- year old and contains necessary bugfixes. Many GNU/Linux distros make
- glibc version 2.3.x available now.
+ C library (glibc) version 2.2.5 which contains necessary bugfixes.
+ Most GNU/Linux distros make more recent versions available now.
+ libstdc++ 4.6.0 and later require glibc 2.3 or later for this
+ localization and formatting code.
</p><p>The guideline is simple: the more recent the C++ library, the
more recent the C library. (This is also documented in the main
GCC installation instructions.)
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.freebsd_wchar"></a><a id="q-freebsd_wchar"></a><p><b>4.8.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="4.8."><td align="left" valign="top"><a id="faq.freebsd_wchar"></a><a id="q-freebsd_wchar"></a><p><b>4.8.</b></p></td><td align="left" valign="top"><p>
Can't use wchar_t/wstring on FreeBSD
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-freebsd_wchar"></a></td><td align="left" valign="top"><p>
Older versions of FreeBSD's C library do not have sufficient
Bugs in the ISO C++ language or library specification
</a></dt><dt>5.3. <a href="faq.html#faq.compiler_bugs">
Bugs in the compiler (gcc/g++) and not libstdc++
- </a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.what_works"></a><a id="q-what_works"></a><p><b>5.1.</b></p></td><td align="left" valign="top"><p>
+ </a></dt></dl></td></tr><tr class="question"
title="5.1."><td align="left" valign="top"><a id="faq.what_works"></a><a id="q-what_works"></a><p><b>5.1.</b></p></td><td align="left" valign="top"><p>
What works already?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-what_works"></a></td><td align="left" valign="top"><p>
Short answer: Pretty much everything <span class="emphasis"><em>works</em></span>
<a class="link" href="manual/status.html#status.iso.1998" title="C++ 1998/2003">C++98</a>,
<a class="link" href="manual/status.html#status.iso.tr1" title="C++ TR1">TR1</a>, and
<a class="link" href="manual/status.html#status.iso.200x" title="C++ 200x">C++0x</a>.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.standard_bugs"></a><a id="q-standard_bugs"></a><p><b>5.2.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="5.2."><td align="left" valign="top"><a id="faq.standard_bugs"></a><a id="q-standard_bugs"></a><p><b>5.2.</b></p></td><td align="left" valign="top"><p>
Bugs in the ISO C++ language or library specification
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-standard_bugs"></a></td><td align="left" valign="top"><p>
Unfortunately, there are some.
For those people who are not part of the ISO Library Group
(i.e., nearly all of us needing to read this page in the first
place), a public list of the library defects is occasionally
- published <a class="ulink" href="http://anubis.dkuug.dk/jtc1/sc22/wg21/" target="_top">here</a>.
+ published <a class="ulink" href="http://www.open-std.org/jtc1/sc22/wg21/" target="_top">here</a>.
Some of these issues have resulted in code changes in libstdc++.
</p><p>
If you think you've discovered a new bug that is not listed,
please post a message describing your problem
to <code class="email"><<a class="email" href="mailto:libstdc++@gcc.gnu.org">libstdc++@gcc.gnu.org</a>></code> or the Usenet group
comp.lang.c++.moderated.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.compiler_bugs"></a><a id="q-compiler_bugs"></a><p><b>5.3.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="5.3."><td align="left" valign="top"><a id="faq.compiler_bugs"></a><a id="q-compiler_bugs"></a><p><b>5.3.</b></p></td><td align="left" valign="top"><p>
Bugs in the compiler (gcc/g++) and not libstdc++
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-compiler_bugs"></a></td><td align="left" valign="top"><p>
On occasion, the compiler is wrong. Please be advised that this
</p><p>
Before reporting a bug, please examine the
<a class="ulink" href="http://gcc.gnu.org/bugs.html" target="_top">bugs database</a> with the
- category set to “<span class="quote">g++</span>”.
+ category set to <span class="quote">“<span class="quote">g++</span>”</span>.
</p></td></tr><tr class="qandadiv"><td align="left" valign="top" colspan="2"><h3 class="title"><a id="faq.known_non-bugs"></a>6. Known Non-Bugs</h3></td></tr><tr class="toc"><td align="left" valign="top" colspan="2"><dl><dt>6.1. <a href="faq.html#faq.stream_reopening_fails">
Reopening a stream fails
</a></dt><dt>6.2. <a href="faq.html#faq.wefcxx_verbose">
list::size() is O(n)!
</a></dt><dt>6.9. <a href="faq.html#faq.easy_to_fix">
Aw, that's easy to fix!
- </a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.stream_reopening_fails"></a><a id="q-stream_reopening_fails"></a><p><b>6.1.</b></p></td><td align="left" valign="top"><p>
+ </a></dt></dl></td></tr><tr class="question"
title="6.1."><td align="left" valign="top"><a id="faq.stream_reopening_fails"></a><a id="q-stream_reopening_fails"></a><p><b>6.1.</b></p></td><td align="left" valign="top"><p>
Reopening a stream fails
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-stream_reopening_fails"></a></td><td align="left" valign="top"><p>
One of the most-reported non-bug reports. Executing a sequence like:
</p><div class="literallayout"><p><br />
#include <fstream><br />
...<br />
- std::fstream fs(“<span class="quote">a_file</span>”);<br />
+ std::fstream fs(<span class="quote">“<span class="quote">a_file</span>”</span>);<br />
// .<br />
// . do things with fs...<br />
// .<br />
fs.close();<br />
- fs.open(“<span class="quote">a_new_file</span>”);<br />
+ fs.open(<span class="quote">“<span class="quote">a_new_file</span>”</span>);<br />
</p></div><p>
All operations on the re-opened <code class="varname">fs</code> will fail, or at
least act very strangely. Yes, they often will, especially if
<span class="emphasis"><em>Update:</em></span> for GCC 4.0 we implemented the resolution
of <a class="link" href="manual/bugs.html" title="Bugs">DR #409</a> and open()
now calls <code class="function">clear()</code> on success!
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.wefcxx_verbose"></a><a id="q-wefcxx_verbose"></a><p><b>6.2.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="6.2."><td align="left" valign="top"><a id="faq.wefcxx_verbose"></a><a id="q-wefcxx_verbose"></a><p><b>6.2.</b></p></td><td align="left" valign="top"><p>
-Weffc++ complains too much
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-wefcxx_verbose"></a></td><td align="left" valign="top"><p>
Many warnings are emitted when <code class="literal">-Weffc++</code> is used. Making
We do, however, try to have libstdc++ sources as clean as possible. If
you see some simple changes that pacify <code class="literal">-Weffc++</code>
without other drawbacks, send us a patch.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.ambiguous_overloads"></a><a id="q-ambiguous_overloads"></a><p><b>6.3.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="6.3."><td align="left" valign="top"><a id="faq.ambiguous_overloads"></a><a id="q-ambiguous_overloads"></a><p><b>6.3.</b></p></td><td align="left" valign="top"><p>
Ambiguous overloads after including an old-style header
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-ambiguous_overloads"></a></td><td align="left" valign="top"><p>
Another problem is the <code class="literal">rel_ops</code> namespace and the template
comparison operator functions contained therein. If they become
visible in the same namespace as other comparison functions
- (e.g., “<span class="quote">using</span>” them and the <iterator> header),
+ (e.g., <span class="quote">“<span class="quote">using</span>”</span> them and the <iterator> header),
then you will suddenly be faced with huge numbers of ambiguity
errors. This was discussed on the -v3 list; Nathan Myers
<a class="ulink" href="http://gcc.gnu.org/ml/libstdc++/2001-01/msg00247.html" target="_top">sums
things up here</a>. The collisions with vector/string iterator
types have been fixed for 3.1.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.v2_headers"></a><a id="q-v2_headers"></a><p><b>6.4.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="6.4."><td align="left" valign="top"><a id="faq.v2_headers"></a><a id="q-v2_headers"></a><p><b>6.4.</b></p></td><td align="left" valign="top"><p>
The g++-3 headers are <span class="emphasis"><em>not ours</em></span>
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-v2_headers"></a></td><td align="left" valign="top"><p>
If you have found an extremely broken header file which is
'v'?). Starting with version 3.2 the headers are installed in
<code class="filename">${prefix}/include/c++/${version}</code> as this prevents
headers from previous versions being found by mistake.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.boost_concept_checks"></a><a id="q-boost_concept_checks"></a><p><b>6.5.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="6.5."><td align="left" valign="top"><a id="faq.boost_concept_checks"></a><a id="q-boost_concept_checks"></a><p><b>6.5.</b></p></td><td align="left" valign="top"><p>
Errors about <span class="emphasis"><em>*Concept</em></span> and
<span class="emphasis"><em>constraints</em></span> in the STL
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-boost_concept_checks"></a></td><td align="left" valign="top"><p>
typo, or wrong visibility, or you just plain forgot, etc).
</p><p>
More information, including how to optionally enable/disable the
- checks, is available
- <a class="link" href="manual/bk01pt03ch08.html" title="Chapter 8. Concept Checking">here</a>.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.dlopen_crash"></a><a id="q-dlopen_crash"></a><p><b>6.6.</b></p></td><td align="left" valign="top"><p>
+ checks, is available in the
+ <a class="link" href="manual/bk01pt02ch05s02.html" title="Concept Checking">Diagnostics</a>.
+ chapter of the manual.
+ </p></td></tr><tr class="question" title="6.6."><td align="left" valign="top"><a id="faq.dlopen_crash"></a><a id="q-dlopen_crash"></a><p><b>6.6.</b></p></td><td align="left" valign="top"><p>
Program crashes when using library code in a
dynamically-loaded library
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-dlopen_crash"></a></td><td align="left" valign="top"><p>
<br />
// link the executable<br />
g++ -fPIC -rdynamic -o foo ... -L. -lfoo -ldl<br />
- </p></div></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.memory_leaks"></a><a id="q-memory_leaks"></a><p><b>6.7.</b></p></td><td align="left" valign="top"><p>
- “<span class="quote">Memory leaks</span>” in containers
+ </p></div></td></tr><tr class="question"
title="6.7."><td align="left" valign="top"><a id="faq.memory_leaks"></a><a id="q-memory_leaks"></a><p><b>6.7.</b></p></td><td align="left" valign="top"><p>
+ <span class="quote">“<span class="quote">Memory leaks</span>”</span> in containers
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-memory_leaks"></a></td><td align="left" valign="top"><p>
A few people have reported that the standard containers appear
to leak memory when tested with memory checkers such as
want to test the library for memory leaks please read
<a class="link" href="manual/debug.html#debug.memory" title="Memory Leak Hunting">Tips for memory leak hunting</a>
first.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.list_size_on"></a><a id="q-list_size_on"></a><p><b>6.8.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="6.8."><td align="left" valign="top"><a id="faq.list_size_on"></a><a id="q-list_size_on"></a><p><b>6.8.</b></p></td><td align="left" valign="top"><p>
list::size() is O(n)!
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-list_size_on"></a></td><td align="left" valign="top"><p>
See
- the <a class="link" href="manual/containers.html" title="Part VII. Containers">Containers</a>
+ the <a class="link" href="manual/containers.html" title="Chapter 9. Containers">Containers</a>
chapter.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.easy_to_fix"></a><a id="q-easy_to_fix"></a><p><b>6.9.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="6.9."><td align="left" valign="top"><a id="faq.easy_to_fix"></a><a id="q-easy_to_fix"></a><p><b>6.9.</b></p></td><td align="left" valign="top"><p>
Aw, that's easy to fix!
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-easy_to_fix"></a></td><td align="left" valign="top"><p>
If you have found a bug in the library and you think you have
What's an ABI and why is it so messy?
</a></dt><dt>7.8. <a href="faq.html#faq.size_equals_capacity">
How do I make std::vector<T>::capacity() == std::vector<T>::size?
- </a></dt></dl></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.iterator_as_pod"></a><a id="faq.iterator_as_pod_q"></a><p><b>7.1.</b></p></td><td align="left" valign="top"><p>
+ </a></dt></dl></td></tr><tr class="question"
title="7.1."><td align="left" valign="top"><a id="faq.iterator_as_pod"></a><a id="faq.iterator_as_pod_q"></a><p><b>7.1.</b></p></td><td align="left" valign="top"><p>
string::iterator is not char*; vector<T>::iterator is not T*
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="faq.iterator_as_pod_a"></a></td><td align="left" valign="top"><p>
If you have code that depends on container<T> iterators
certain expressions to <code class="varname">&*i</code>. Future revisions
of the Standard are expected to bless this usage for
vector<> (but not for basic_string<>).
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.what_is_next"></a><a id="q-what_is_next"></a><p><b>7.2.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="7.2."><td align="left" valign="top"><a id="faq.what_is_next"></a><a id="q-what_is_next"></a><p><b>7.2.</b></p></td><td align="left" valign="top"><p>
What's next after libstdc++?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-what_is_next"></a></td><td align="left" valign="top"><p>
Hopefully, not much. The goal of libstdc++ is to produce a
this effort is described in
<a class="ulink" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf" target="_top">
The C++ Library Technical Report 1</a>.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.sgi_stl"></a><a id="q-sgi_stl"></a><p><b>7.3.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="7.3."><td align="left" valign="top"><a id="faq.sgi_stl"></a><a id="q-sgi_stl"></a><p><b>7.3.</b></p></td><td align="left" valign="top"><p>
What about the STL from SGI?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-sgi_stl"></a></td><td align="left" valign="top"><p>
The <a class="ulink" href="http://www.sgi.com/tech/stl/" target="_top">STL from SGI</a>,
</p><p>
The FAQ for SGI's STL (one jump off of their main page) is
still recommended reading.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.extensions_and_backwards_compat"></a><a id="q-extensions_and_backwards_compat"></a><p><b>7.4.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="7.4."><td align="left" valign="top"><a id="faq.extensions_and_backwards_compat"></a><a id="q-extensions_and_backwards_compat"></a><p><b>7.4.</b></p></td><td align="left" valign="top"><p>
Extensions and Backward Compatibility
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-extensions_and_backwards_compat"></a></td><td align="left" valign="top"><p>
See the <a class="link" href="manual/backwards.html" title="Backwards Compatibility">link</a> on backwards compatibility and <a class="link" href="manual/api.html" title="API Evolution and Deprecation History">link</a> on evolution.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.tr1_support"></a><a id="q-tr1_support"></a><p><b>7.5.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="7.5."><td align="left" valign="top"><a id="faq.tr1_support"></a><a id="q-tr1_support"></a><p><b>7.5.</b></p></td><td align="left" valign="top"><p>
Does libstdc++ support TR1?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-tr1_support"></a></td><td align="left" valign="top"><p>
Yes.
</p><p>
The implementation status of TR1 in libstdc++ can be tracked <a class="link" href="manual/status.html#status.iso.tr1" title="C++ TR1">on the TR1 status
page</a>.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.get_iso_cxx"></a><a id="q-get_iso_cxx"></a><p><b>7.6.</b></p></td><td align="left" valign="top"><p>How do I get a copy of the ISO C++ Standard?
+ </p></td></tr><tr class="question"
title="7.6."><td align="left" valign="top"><a id="faq.get_iso_cxx"></a><a id="q-get_iso_cxx"></a><p><b>7.6.</b></p></td><td align="left" valign="top"><p>How do I get a copy of the ISO C++ Standard?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-get_iso_cxx"></a></td><td align="left" valign="top"><p>
Copies of the full ISO 14882 standard are available on line via
the ISO mirror site for committee members. Non-members, or those
right <a class="ulink" href="http://www.ansi.org" target="_top">here</a>. (And if
you've already registered with them, clicking this link will take
you to directly to the place where you can
- <a class="ulink" href="http://webstore.ansi.org/ansidocstore/product.asp?sku=ISO%2FIEC+14882%3A2003" target="_top">buy the standard on-line</a>.
+ <a class="ulink" href="http://webstore.ansi.org/RecordDetail.aspx?sku=ISO%2FIEC+14882:2003" target="_top">buy the standard on-line</a>.
</p><p>
Who is your country's member body? Visit the
<a class="ulink" href="http://www.iso.ch/" target="_top">ISO homepage</a> and find out!
</p><p>
The 2003 version of the standard (the 1998 version plus TC1) is
available in print, ISBN 0-470-84674-7.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.what_is_abi"></a><a id="q-what_is_abi"></a><p><b>7.7.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="7.7."><td align="left" valign="top"><a id="faq.what_is_abi"></a><a id="q-what_is_abi"></a><p><b>7.7.</b></p></td><td align="left" valign="top"><p>
What's an ABI and why is it so messy?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-what_is_abi"></a></td><td align="left" valign="top"><p>
- <acronym class="acronym">ABI</acronym> stands for “<span class="quote">Application Binary
- Interface</span>”. Conventionally, it refers to a great
+ <acronym class="acronym">ABI</acronym> stands for <span class="quote">“<span class="quote">Application Binary
+ Interface</span>”</span>. Conventionally, it refers to a great
mass of details about how arguments are arranged on the call
stack and/or in registers, and how various types are arranged
and padded in structs. A single CPU design may suffer
virtual function implementation, struct inheritance layout, name
mangling, and exception handling. Such an ABI has been defined for
GNU C++, and is immediately useful for embedded work relying only on
- a “<span class="quote">free-standing implementation</span>” that doesn't include (much
+ a <span class="quote">“<span class="quote">free-standing implementation</span>”</span> that doesn't include (much
of) the standard library. It is a good basis for the work to come.
</p><p>
A useful C++ ABI must also incorporate many details of the standard
so they may later be changed. Deciding which, and implementing
the decisions, must happen before you can reasonably document a
candidate C++ ABI that encompasses the standard library.
- </p></td></tr><tr class="question"><td align="left" valign="top"><a id="faq.size_equals_capacity"></a><a id="q-size_equals_capacity"></a><p><b>7.8.</b></p></td><td align="left" valign="top"><p>
+ </p></td></tr><tr class="question"
title="7.8."><td align="left" valign="top"><a id="faq.size_equals_capacity"></a><a id="q-size_equals_capacity"></a><p><b>7.8.</b></p></td><td align="left" valign="top"><p>
How do I make std::vector<T>::capacity() == std::vector<T>::size?
</p></td></tr><tr class="answer"><td align="left" valign="top"><a id="a-size_equals_capacity"></a></td><td align="left" valign="top"><p>
The standard idiom for deallocating a <code class="classname">vector<T></code>'s
</p></div><p>
The copy will take O(n) time and the swap is constant time.
</p><p>
- See <a class="link" href="manual/bk01pt05ch13s05.html" title="Shrink to Fit">Shrink-to-fit
+ See <a class="link" href="manual/strings.html#strings.string.shrink" title="Shrink to Fit">Shrink-to-fit
strings</a> for a similar solution for strings.
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