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| <meta name="AUTHOR" content="pme@gcc.gnu.org (Phil Edwards)" /> |
| <meta name="KEYWORDS" content="libstdc++, libstdc++-v3, GCC, g++" /> |
| <meta name="DESCRIPTION" content="Explanatory notes about libstdc++-v3." /> |
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| <h1 class="centered"><a name="top">Explanatory notes about libstdc++-v3 |
| design</a></h1> |
| |
| <p class="fineprint"><em> |
| The latest version of this document is always available at |
| <a href="http://gcc.gnu.org/onlinedocs/libstdc++/explanations.html"> |
| http://gcc.gnu.org/onlinedocs/libstdc++/explanations.html</a>. |
| </em></p> |
| |
| <p><em> |
| To the <a href="http://gcc.gnu.org/libstdc++/">libstdc++-v3 homepage</a>. |
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| <h3><a name="cstdio">"I/O packages", <code>--enable-cstdio</code></a></h3> |
| <p>In addition to all the nifty things which C++ can do for I/O, its library |
| also includes all of the I/O capabilites of C. Making them work together |
| can be a challenge, not only |
| <a href="27_io/howto.html#8">for the programmer</a> but for the |
| implementors as well. |
| </p> |
| <p>There are two ways to do a C++ library: the cool way, and the easy way. |
| More specifically, the cool-but-easy-to-get-wrong way, and the |
| easy-to-guarantee-correct-behavior way. For 3.0, the easy way is used. |
| </p> |
| <p>Choosing 'stdio' is the easy way. It builds a C++ library which forwards |
| all operations to the C library. Many of the C++ I/O functions are |
| specified in the standard 'as if' they called a certain C function; the |
| easiest way to get it correct is to actually call that function. The |
| disadvantage is that the C++ code will run slower (fortunately, the layer |
| is thin). |
| </p> |
| <p>Other packages are possible. For a new package, a header must be |
| written to provide types like streamsize (usually just a typedef), as |
| well as some internal types like<code> __c_file_type </code> and |
| <code> __c_lock </code> (for the stdio case, these are FILE (as in |
| "FILE*") and a simple POSIX mutex, respectively). An |
| interface class called <code> __basic_file </code> must also be filled in; |
| as an example, for the stdio case, these member functions are all |
| inline calles to fread, fwrite, etc. |
| </p> |
| <p>Return <a href="#top">to the top of the page</a> or |
| <a href="http://gcc.gnu.org/libstdc++/">to the homepage</a>. |
| </p> |
| |
| |
| <hr /> |
| <h3><a name="alloc">Internal Allocators</a></h3> |
| <p> |
| </p> |
| <p>Return <a href="#top">to the top of the page</a> or |
| <a href="http://gcc.gnu.org/libstdc++/">to the homepage</a>. |
| </p> |
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| See <a href="17_intro/license.html">license.html</a> for copying conditions. |
| Comments and suggestions are welcome, and may be sent to |
| <a href="mailto:libstdc++@gcc.gnu.org">the libstdc++ mailing list</a>. |
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