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| <html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 25. Stream Buffers</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /><meta name="keywords" content=" ISO C++ , library " /><link rel="start" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="io.html" title="Part XI. Input and Output" /><link rel="prev" href="bk01pt11ch24.html" title="Chapter 24. Iostream Objects" /><link rel="next" href="bk01pt11ch25s02.html" title="Buffering" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 25. Stream Buffers</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="bk01pt11ch24.html">Prev</a> </td><th width="60%" align="center">Part XI. Input and Output</th><td width="20%" align="right"> <a accesskey="n" href="bk01pt11ch25s02.html">Next</a></td></tr></table><hr /></div><div class="chapter" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title"><a id="manual.io.streambufs"></a>Chapter 25. Stream Buffers</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="bk01pt11ch25.html#io.streambuf.derived">Derived streambuf Classes</a></span></dt><dt><span class="sect1"><a href="bk01pt11ch25s02.html">Buffering</a></span></dt></dl></div><div class="sect1" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="io.streambuf.derived"></a>Derived streambuf Classes</h2></div></div></div><p> |
| </p><p>Creating your own stream buffers for I/O can be remarkably easy. |
| If you are interested in doing so, we highly recommend two very |
| excellent books: |
| <a class="ulink" href="http://www.langer.camelot.de/iostreams.html" target="_top">Standard C++ |
| IOStreams and Locales</a> by Langer and Kreft, ISBN 0-201-18395-1, and |
| <a class="ulink" href="http://www.josuttis.com/libbook/" target="_top">The C++ Standard Library</a> |
| by Nicolai Josuttis, ISBN 0-201-37926-0. Both are published by |
| Addison-Wesley, who isn't paying us a cent for saying that, honest. |
| </p><p>Here is a simple example, io/outbuf1, from the Josuttis text. It |
| transforms everything sent through it to uppercase. This version |
| assumes many things about the nature of the character type being |
| used (for more information, read the books or the newsgroups): |
| </p><pre class="programlisting"> |
| #include <iostream> |
| #include <streambuf> |
| #include <locale> |
| #include <cstdio> |
| |
| class outbuf : public std::streambuf |
| { |
| protected: |
| /* central output function |
| * - print characters in uppercase mode |
| */ |
| virtual int_type overflow (int_type c) { |
| if (c != EOF) { |
| // convert lowercase to uppercase |
| c = std::toupper(static_cast<char>(c),getloc()); |
| |
| // and write the character to the standard output |
| if (putchar(c) == EOF) { |
| return EOF; |
| } |
| } |
| return c; |
| } |
| }; |
| |
| int main() |
| { |
| // create special output buffer |
| outbuf ob; |
| // initialize output stream with that output buffer |
| std::ostream out(&ob); |
| |
| out << "31 hexadecimal: " |
| << std::hex << 31 << std::endl; |
| return 0; |
| } |
| </pre><p>Try it yourself! More examples can be found in 3.1.x code, in |
| <code class="code">include/ext/*_filebuf.h</code>, and on |
| <a class="ulink" href="http://www.informatik.uni-konstanz.de/~kuehl/c++/iostream/" target="_top">Dietmar |
| Kühl's IOStreams page</a>. |
| </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="bk01pt11ch24.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="io.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="bk01pt11ch25s02.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 24. Iostream Objects </td><td width="20%" align="center"><a accesskey="h" href="../spine.html">Home</a></td><td width="40%" align="right" valign="top"> Buffering</td></tr></table></div></body></html> |
