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-<html xmlns="http://www.w3.org/1999/xhtml"><head><title>Backwards Compatibility</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.7
5.2"/><meta name="keywords" content=" ISO C++ , backwards "/><meta name="keywords" content=" ISO C++ , library "/><link rel="home" href="../spine.html" title="The GNU C++ Library"/><link rel="up" href="appendix_porting.html" title="Appendix B. Porting and Maintenance"/><link rel="prev" href="api.html" title="API Evolution and Deprecation History"/><link rel="next" href="appendix_free.html" title="Appendix C. Free Software Needs Free Documentation"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Backwards Compatibility</th></tr><tr><td align="left"><a accesskey="p" href="api.html">Prev</a> </td><th width="60%" align="center">Appendix B.
+<html xmlns="http://www.w3.org/1999/xhtml"><head><title>Backwards Compatibility</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.7
6.1"/><meta name="keywords" content=" ISO C++ , backwards "/><meta name="keywords" content=" ISO C++ , library "/><link rel="home" href="../spine.html" title="The GNU C++ Library"/><link rel="up" href="appendix_porting.html" title="Appendix B. Porting and Maintenance"/><link rel="prev" href="api.html" title="API Evolution and Deprecation History"/><link rel="next" href="appendix_free.html" title="Appendix C. Free Software Needs Free Documentation"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Backwards Compatibility</th></tr><tr><td align="left"><a accesskey="p" href="api.html">Prev</a> </td><th width="60%" align="center">Appendix B.
Porting and Maintenance
</th><td align="right"> <a accesskey="n" href="appendix_free.html">Next</a></td></tr></table><hr/></div><div class="section" title="Backwards Compatibility"><div class="titlepage"><div><div><h2 class="title"><a id="manual.appendix.porting.backwards"/>Backwards Compatibility</h2></div></div></div><div class="section" title="First"><div class="titlepage"><div><div><h3 class="title"><a id="backwards.first"/>First</h3></div></div></div><p>The first generation GNU C++ library was called libg++. It was a
really useful things that are used by a lot of people, the Standards
Committee couldn't include everything, and so a lot of those
<span class="quote">“<span class="quote">obvious</span>”</span> classes didn't get included.
-</p><p>Known Issues include many of the limitations of its immediate ancestor.</p><p>Portability notes and known implementation limitations are as follows.</p><div class="section" title="No ios_base"><div class="titlepage"><div><div><h4 class="title"><a id="id
624435"/>No <code class="code">ios_base</code></h4></div></div></div><p> At least some older implementations don't have <code class="code">std::ios_base</code>, so you should use <code class="code">std::ios::badbit</code>, <code class="code">std::ios::failbit</code> and <code class="code">std::ios::eofbit</code> and <code class="code">std::ios::goodbit</code>.
-</p></div><div class="section" title="No cout in ostream.h, no cin in istream.h"><div class="titlepage"><div><div><h4 class="title"><a id="id
624468"/>No <code class="code">cout</code> in <code class="code">ostream.h</code>, no <code class="code">cin</code> in <code class="code">istream.h</code></h4></div></div></div><p>
+</p><p>Known Issues include many of the limitations of its immediate ancestor.</p><p>Portability notes and known implementation limitations are as follows.</p><div class="section" title="No ios_base"><div class="titlepage"><div><div><h4 class="title"><a id="id
585504"/>No <code class="code">ios_base</code></h4></div></div></div><p> At least some older implementations don't have <code class="code">std::ios_base</code>, so you should use <code class="code">std::ios::badbit</code>, <code class="code">std::ios::failbit</code> and <code class="code">std::ios::eofbit</code> and <code class="code">std::ios::goodbit</code>.
+</p></div><div class="section" title="No cout in ostream.h, no cin in istream.h"><div class="titlepage"><div><div><h4 class="title"><a id="id
585536"/>No <code class="code">cout</code> in <code class="code">ostream.h</code>, no <code class="code">cin</code> in <code class="code">istream.h</code></h4></div></div></div><p>
In earlier versions of the standard,
<code class="filename">fstream.h</code>,
<code class="filename">ostream.h</code>
explicitly to get the required definitions.
</p><p> Some include adjustment may be required.</p><p>This project is no longer maintained or supported, and the sources
archived. For the desperate,
-the <a class="link" href="http://gcc.gnu.org/extensions.html" target="">GCC extensions
+the <a class="link" href="http://gcc.gnu.org/extensions.html">GCC extensions
page</a> describes where to find the last libg++ source. The code is
considered replaced and rewritten.
</p></div></div><div class="section" title="Second"><div class="titlepage"><div><div><h3 class="title"><a id="backwards.second"/>Second</h3></div></div></div><p>
archived. The code is considered replaced and rewritten.
</p><p>
Portability notes and known implementation limitations are as follows.
-</p><div class="section" title="Namespace std:: not supported"><div class="titlepage"><div><div><h4 class="title"><a id="id
624570"/>Namespace <code class="code">std::</code> not supported</h4></div></div></div><p>
+</p><div class="section" title="Namespace std:: not supported"><div class="titlepage"><div><div><h4 class="title"><a id="id
585639"/>Namespace <code class="code">std::</code> not supported</h4></div></div></div><p>
Some care is required to support C++ compiler and or library
implementation that do not have the standard library in
<code class="code">namespace std</code>.
AC_DEFINE(HAVE_NAMESPACE_STD,,[Define if g++ supports namespace std. ])
fi
])
-</pre></div><div class="section" title="Illegal iterator usage"><div class="titlepage"><div><div><h4 class="title"><a id="id
624697"/>Illegal iterator usage</h4></div></div></div><p>
+</pre></div><div class="section" title="Illegal iterator usage"><div class="titlepage"><div><div><h4 class="title"><a id="id
585765"/>Illegal iterator usage</h4></div></div></div><p>
The following illustrate implementation-allowed illegal iterator
use, and then correct use.
</p><div class="itemizedlist"><ul class="itemizedlist"><li class="listitem"><p>
</p></li><li class="listitem"><p>
<code class="code">if (iterator)</code> won't work any more => use
<code class="code">if (iterator != iterator_type())</code>
- </p></li></ul></div></div><div class="section" title="isspace from cctype is a macro"><div class="titlepage"><div><div><h4 class="title"><a id="id624758"/><code class="code">isspace</code> from <code class="filename">cctype</code> is a macro
+ </p></li></ul></div></div><div class="section" title="isspace from cctype is a macro"><div class="titlepage"><div><div><h4 class="title"><a id="id585827"/><code class="code">isspace</code> from <code class="filename">cctype</code> is a macro
</h4></div></div></div><p>
Glibc 2.0.x and 2.1.x define <code class="filename">ctype.h</code> functionality as macros
(isspace, isalpha etc.).
(<code class="filename">ctype.h</code>) and the
definitions in namespace <code class="code">std::</code>
(<code class="code"><cctype></code>).
-</p></div><div class="section" title="No vector::at, deque::at, string::at"><div class="titlepage"><div><div><h4 class="title"><a id="id
624854"/>No <code class="code">vector::at</code>, <code class="code">deque::at</code>, <code class="code">string::at</code></h4></div></div></div><p>
+</p></div><div class="section" title="No vector::at, deque::at, string::at"><div class="titlepage"><div><div><h4 class="title"><a id="id
585922"/>No <code class="code">vector::at</code>, <code class="code">deque::at</code>, <code class="code">string::at</code></h4></div></div></div><p>
One solution is to add an autoconf-test for this:
</p><pre class="programlisting">
AC_MSG_CHECKING(for container::at)
</pre><p>
If you are using other (non-GNU) compilers it might be a good idea
to check for <code class="code">string::at</code> separately.
-</p></div><div class="section" title="No std::char_traits<char>::eof"><div class="titlepage"><div><div><h4 class="title"><a id="id
624893"/>No <code class="code">std::char_traits<char>::eof</code></h4></div></div></div><p>
+</p></div><div class="section" title="No std::char_traits<char>::eof"><div class="titlepage"><div><div><h4 class="title"><a id="id
585961"/>No <code class="code">std::char_traits<char>::eof</code></h4></div></div></div><p>
Use some kind of autoconf test, plus this:
</p><pre class="programlisting">
#ifdef HAVE_CHAR_TRAITS
#else
#define CPP_EOF EOF
#endif
-</pre></div><div class="section" title="No string::clear"><div class="titlepage"><div><div><h4 class="title"><a id="id
624911"/>No <code class="code">string::clear</code></h4></div></div></div><p>
+</pre></div><div class="section" title="No string::clear"><div class="titlepage"><div><div><h4 class="title"><a id="id
585980"/>No <code class="code">string::clear</code></h4></div></div></div><p>
There are two functions for deleting the contents of a string:
<code class="code">clear</code> and <code class="code">erase</code> (the latter returns the
string).
Unfortunately, <code class="code">clear</code> is not implemented in this
version, so you should use <code class="code">erase</code> (which is probably
faster than <code class="code">operator=(charT*)</code>).
-</p></div><div class="section" title="Removal of ostream::form and istream::scan extensions"><div class="titlepage"><div><div><h4 class="title"><a id="id624957"/>
+</p></div><div class="section" title="Removal of ostream::form and istream::scan extensions"><div class="titlepage"><div><div><h4 class="title"><a id="id586025"/>
Removal of <code class="code">ostream::form</code> and <code class="code">istream::scan</code>
extensions
</h4></div></div></div><p>
These are no longer supported. Please use stringstreams instead.
-</p></div><div class="section" title="No basic_stringbuf, basic_stringstream"><div class="titlepage"><div><div><h4 class="title"><a id="id
624976"/>No <code class="code">basic_stringbuf</code>, <code class="code">basic_stringstream</code></h4></div></div></div><p>
+</p></div><div class="section" title="No basic_stringbuf, basic_stringstream"><div class="titlepage"><div><div><h4 class="title"><a id="id
586044"/>No <code class="code">basic_stringbuf</code>, <code class="code">basic_stringstream</code></h4></div></div></div><p>
Although the ISO standard <code class="code">i/ostringstream</code>-classes are
provided, (<code class="filename">sstream</code>), for
compatibility with older implementations the pre-ISO
Another example of using stringstreams is in <a class="link" href="strings.html#strings.string.shrink" title="Shrink to Fit">this howto</a>.
</p><p> There is additional information in the libstdc++-v2 info files, in
particular <span class="quote">“<span class="quote">info iostream</span>”</span>.
-</p></div><div class="section" title="Little or no wide character support"><div class="titlepage"><div><div><h4 class="title"><a id="id
625132"/>Little or no wide character support</h4></div></div></div><p>
+</p></div><div class="section" title="Little or no wide character support"><div class="titlepage"><div><div><h4 class="title"><a id="id
586200"/>Little or no wide character support</h4></div></div></div><p>
Classes <code class="classname">wstring</code> and
<code class="classname">char_traits<wchar_t></code> are
not supported.
- </p></div><div class="section" title="No templatized iostreams"><div class="titlepage"><div><div><h4 class="title"><a id="id
625150"/>No templatized iostreams</h4></div></div></div><p>
+ </p></div><div class="section" title="No templatized iostreams"><div class="titlepage"><div><div><h4 class="title"><a id="id
586219"/>No templatized iostreams</h4></div></div></div><p>
Classes <code class="classname">wfilebuf</code> and
<code class="classname">wstringstream</code> are not supported.
- </p></div><div class="section" title="Thread safety issues"><div class="titlepage"><div><div><h4 class="title"><a id="id
625169"/>Thread safety issues</h4></div></div></div><p>
+ </p></div><div class="section" title="Thread safety issues"><div class="titlepage"><div><div><h4 class="title"><a id="id
586237"/>Thread safety issues</h4></div></div></div><p>
Earlier GCC releases had a somewhat different approach to
threading configuration and proper compilation. Before GCC 3.0,
configuration of the threading model was dictated by compiler
against the gthr.h abstraction layer which is provided by gcc. A
minor problem that pops up every so often is different
interpretations of what "thread-safe" means for a
- library (not a general program). We currently use the <a class="link" href="http://www.sgi.com/tech/stl/thread_safety.html" target="">same
+ library (not a general program). We currently use the <a class="link" href="http://www.sgi.com/tech/stl/thread_safety.html">same
definition that SGI</a> uses for their STL subset. However,
the exception for read-only containers only applies to the STL
components. This definition is widely-used and something similar
"Thread Next" to move down the thread. This farm is in
latest-to-oldest order.
</p><div class="itemizedlist"><ul class="itemizedlist"><li class="listitem"><p>
- Our threading expert Loren gives a breakdown of <a class="link" href="http://gcc.gnu.org/ml/libstdc++/2001-10/msg00024.html" target="">the
+ Our threading expert Loren gives a breakdown of <a class="link" href="http://gcc.gnu.org/ml/libstdc++/2001-10/msg00024.html">the
six situations involving threads</a> for the 3.0
release series.
</p></li><li class="listitem"><p>
- <a class="link" href="http://gcc.gnu.org/ml/libstdc++/2001-05/msg00384.html" target="">
+ <a class="link" href="http://gcc.gnu.org/ml/libstdc++/2001-05/msg00384.html">
This message</a> inspired a recent updating of issues with
threading and the SGI STL library. It also contains some
example POSIX-multithreaded STL code.
of the SGI STL (version 3.3), with extensive changes.
</p><p>A more formal description of the V3 goals can be found in the
official <a class="link" href="source_design_notes.html" title="Design Notes">design document</a>.
- </p><p>Portability notes and known implementation limitations are as follows.</p><div class="section" title="Pre-ISO headers moved to backwards or removed"><div class="titlepage"><div><div><h4 class="title"><a id="id
625293"/>Pre-ISO headers moved to backwards or removed</h4></div></div></div><p> The pre-ISO C++ headers
+ </p><p>Portability notes and known implementation limitations are as follows.</p><div class="section" title="Pre-ISO headers moved to backwards or removed"><div class="titlepage"><div><div><h4 class="title"><a id="id
586362"/>Pre-ISO headers moved to backwards or removed</h4></div></div></div><p> The pre-ISO C++ headers
(<code class="code">iostream.h</code>, <code class="code">defalloc.h</code> etc.) are
available, unlike previous libstdc++ versions, but inclusion
generates a warning that you are using deprecated headers.
<code class="code">std::</code> into the global namespace.
</p><p>For those of you new to ISO C++ (welcome, time travelers!), no,
that isn't a typo. Yes, the headers really have new names.
- Marshall Cline's C++ FAQ Lite has a good explanation in <a class="link" href="http://www.parashift.com/c++-faq-lite/coding-standards.html#faq-27.4" target="">item
+ Marshall Cline's C++ FAQ Lite has a good explanation in <a class="link" href="http://www.parashift.com/c++-faq-lite/coding-standards.html#faq-27.4">item
[27.4]</a>.
</p><p> Some include adjustment may be required. What follows is an
autoconf test that defines <code class="code">PRE_STDCXX_HEADERS</code> when they
directive <code class="code">using namespace std;</code> can be put at the global
scope. This should be enough to get this code compiling, assuming the
other usage is correct.
-</p></div><div class="section" title="Extension headers hash_map, hash_set moved to ext or backwards"><div class="titlepage"><div><div><h4 class="title"><a id="id
625378"/>Extension headers hash_map, hash_set moved to ext or backwards</h4></div></div></div><p>At this time most of the features of the SGI STL extension have been
+</p></div><div class="section" title="Extension headers hash_map, hash_set moved to ext or backwards"><div class="titlepage"><div><div><h4 class="title"><a id="id
586446"/>Extension headers hash_map, hash_set moved to ext or backwards</h4></div></div></div><p>At this time most of the features of the SGI STL extension have been
replaced by standardized libraries.
In particular, the unordered_map and unordered_set containers of TR1
are suitable replacement for the non-standard hash_map and hash_set
AC_DEFINE(HAVE_EXT_HASH_SET,,[Define if ext/hash_set is present. ])
fi
])
-</pre></div><div class="section" title="No ios::nocreate/ios::noreplace."><div class="titlepage"><div><div><h4 class="title"><a id="id625481"/>No <code class="code">ios::nocreate/ios::noreplace</code>.
+</pre></div><div class="section" title="No ios::nocreate/ios::noreplace."><div class="titlepage"><div><div><h4 class="title"><a id="id586550"/>No <code class="code">ios::nocreate/ios::noreplace</code>.
</h4></div></div></div><p> The existence of <code class="code">ios::nocreate</code> being used for
input-streams has been confirmed, most probably because the author
thought it would be more correct to specify nocreate explicitly. So
decide whether you want to create/replace or not. To my knowledge,
even older implementations support <code class="code">app</code>, <code class="code">ate</code>
and <code class="code">trunc</code> (except for <code class="code">app</code> ?).
-</p></div><div class="section" title="No stream::attach(int fd)"><div class="titlepage"><div><div><h4 class="title"><a id="id625529"/>
+</p></div><div class="section" title="No stream::attach(int fd)"><div class="titlepage"><div><div><h4 class="title"><a id="id586597"/>
No <code class="code">stream::attach(int fd)</code>
</h4></div></div></div><p>
Phil Edwards writes: It was considered and rejected for the ISO
</p><p>
An extension is available that implements this.
<code class="filename">ext/stdio_filebuf.h</code> contains a derived class called
- <a class="link" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a00074.html" target=""><code class="code">__gnu_cxx::stdio_filebuf</code></a>.
+ <a class="link" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a00074.html"><code class="code">__gnu_cxx::stdio_filebuf</code></a>.
This class can be constructed from a C <code class="code">FILE*</code> or a file
descriptor, and provides the <code class="code">fd()</code> function.
</p><p>
For another example of this, refer to
- <a class="link" href="http://www.josuttis.com/cppcode/fdstream.html" target="">fdstream example</a>
+ <a class="link" href="http://www.josuttis.com/cppcode/fdstream.html">fdstream example</a>
by Nicolai Josuttis.
-</p></div><div class="section" title="Support for C++98 dialect."><div class="titlepage"><div><div><h4 class="title"><a id="id625597"/>
+</p></div><div class="section" title="Support for C++98 dialect."><div class="titlepage"><div><div><h4 class="title"><a id="id586665"/>
Support for C++98 dialect.
</h4></div></div></div><p>Check for complete library coverage of the C++1998/2003 standard.
</p><pre class="programlisting">
AC_DEFINE(STDCXX_98_HEADERS,,[Define if ISO C++ 1998 header files are present. ])
fi
])
-</pre></div><div class="section" title="Support for C++TR1 dialect."><div class="titlepage"><div><div><h4 class="title"><a id="id625624"/>
+</pre></div><div class="section" title="Support for C++TR1 dialect."><div class="titlepage"><div><div><h4 class="title"><a id="id586693"/>
Support for C++TR1 dialect.
</h4></div></div></div><p>Check for library coverage of the TR1 standard.
</p><pre class="programlisting">
AC_DEFINE(HAVE_TR1_UNORDERED_SET,,[Define if tr1/unordered_set is present. ])
fi
])
-</pre></div><div class="section" title="Support for C++0x dialect."><div class="titlepage"><div><div><h4 class="title"><a id="id625668"/>
+</pre></div><div class="section" title="Support for C++0x dialect."><div class="titlepage"><div><div><h4 class="title"><a id="id586737"/>
Support for C++0x dialect.
</h4></div></div></div><p>Check for baseline language coverage in the compiler for the C++0xstandard.
</p><pre class="programlisting">
AC_DEFINE(HAVE_UNORDERED_SET,,[Define if unordered_set is present. ])
fi
])
-</pre></div><div class="section" title="Container::iterator_type is not necessarily Container::value_type*"><div class="titlepage"><div><div><h4 class="title"><a id="id625747"/>
+</pre></div><div class="section" title="Container::iterator_type is not necessarily Container::value_type*"><div class="titlepage"><div><div><h4 class="title"><a id="id586815"/>
Container::iterator_type is not necessarily Container::value_type*
</h4></div></div></div><p>
This is a change in behavior from the previous version. Now, most
<span class="type">iterator_type</span> typedefs in container classes are POD
objects, not <span class="type">value_type</span> pointers.
-</p></div></div><div class="bibliography" title="Bibliography"><div class="titlepage"><div><div><h3 class="title"><a id="backwards.biblio"/>Bibliography</h3></div></div></div><div class="biblioentry"><a id="id
625777"/><p><span class="biblioid">
+</p></div></div><div class="bibliography" title="Bibliography"><div class="titlepage"><div><div><h3 class="title"><a id="backwards.biblio"/>Bibliography</h3></div></div></div><div class="biblioentry"><a id="id
586846"/><p><span class="biblioid">
. </span><span class="citetitle"><em class="citetitle">
Migrating to GCC 4.1
- </em>. </span><span class="author"><span class="firstname">Dan</span> <span class="surname">Kegel</span>. </span></p></div><div class="biblioentry"><a id="id
625802"/><p><span class="biblioid">
+ </em>. </span><span class="author"><span class="firstname">Dan</span> <span class="surname">Kegel</span>. </span></p></div><div class="biblioentry"><a id="id
586871"/><p><span class="biblioid">
. </span><span class="citetitle"><em class="citetitle">
Building the Whole Debian Archive with GCC 4.1: A Summary
- </em>. </span><span class="author"><span class="firstname">Martin</span> <span class="surname">Michlmayr</span>. </span></p></div><div class="biblioentry"><a id="id
625828"/><p><span class="biblioid">
+ </em>. </span><span class="author"><span class="firstname">Martin</span> <span class="surname">Michlmayr</span>. </span></p></div><div class="biblioentry"><a id="id
586897"/><p><span class="biblioid">
. </span><span class="citetitle"><em class="citetitle">
Migration guide for GCC-3.2
</em>. </span></p></div></div></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td align="left"><a accesskey="p" href="api.html">Prev</a> </td><td align="center"><a accesskey="u" href="appendix_porting.html">Up</a></td><td align="right"> <a accesskey="n" href="appendix_free.html">Next</a></td></tr><tr><td align="left" valign="top">API Evolution and Deprecation History </td><td align="center"><a accesskey="h" href="../spine.html">Home</a></td><td align="right" valign="top"> Appendix C.
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