1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Memory Based Streams</title><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="io.html" title="Chapter��13.�� Input and Output" /><link rel="prev" href="streambufs.html" title="Stream Buffers" /><link rel="next" href="fstreams.html" title="File Based Streams" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Memory Based Streams</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="streambufs.html">Prev</a>��</td><th width="60%" align="center">Chapter��13.�� 3 Input and Output 4 5</th><td width="20%" align="right">��<a accesskey="n" href="fstreams.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="std.io.memstreams"></a>Memory Based Streams</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="std.io.memstreams.compat"></a>Compatibility With strstream</h3></div></div></div><p> 6 </p><p>Stringstreams (defined in the header <code class="code"><sstream></code>) 7 are in this author's opinion one of the coolest things since 8 sliced time. An example of their use is in the Received Wisdom 9 section for Sect1 21 (Strings), 10 <a class="link" href="strings.html#strings.string.Cstring" title="CString (MFC)"> describing how to 11 format strings</a>. 12 </p><p>The quick definition is: they are siblings of ifstream and ofstream, 13 and they do for <code class="code">std::string</code> what their siblings do for 14 files. All that work you put into writing <code class="code"><<</code> and 15 <code class="code">>></code> functions for your classes now pays off 16 <span class="emphasis"><em>again!</em></span> Need to format a string before passing the string 17 to a function? Send your stuff via <code class="code"><<</code> to an 18 ostringstream. You've read a string as input and need to parse it? 19 Initialize an istringstream with that string, and then pull pieces 20 out of it with <code class="code">>></code>. Have a stringstream and need to 21 get a copy of the string inside? Just call the <code class="code">str()</code> 22 member function. 23 </p><p>This only works if you've written your 24 <code class="code"><<</code>/<code class="code">>></code> functions correctly, though, 25 and correctly means that they take istreams and ostreams as 26 parameters, not i<span class="emphasis"><em>f</em></span>streams and o<span class="emphasis"><em>f</em></span>streams. If they 27 take the latter, then your I/O operators will work fine with 28 file streams, but with nothing else -- including stringstreams. 29 </p><p>If you are a user of the strstream classes, you need to update 30 your code. You don't have to explicitly append <code class="code">ends</code> to 31 terminate the C-style character array, you don't have to mess with 32 "freezing" functions, and you don't have to manage the 33 memory yourself. The strstreams have been officially deprecated, 34 which means that 1) future revisions of the C++ Standard won't 35 support them, and 2) if you use them, people will laugh at you. 36 </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="streambufs.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="fstreams.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Stream Buffers��</td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top">��File Based Streams</td></tr></table></div></body></html>