<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>buffer</title> <link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../../boost_asio.html" title="Boost.Asio"> <link rel="up" href="../reference.html" title="Reference"> <link rel="prev" href="basic_yield_context/operator_lb__rb_.html" title="basic_yield_context::operator[]"> <link rel="next" href="buffer/overload1.html" title="buffer (1 of 28 overloads)"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td> <td align="center"><a href="../../../../index.html">Home</a></td> <td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td> <td align="center"><a 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class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span></code> function is used to create a buffer object to represent raw memory, an array of POD elements, a vector of POD elements, or a std::string. </p> <pre class="programlisting"><span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload1.html" title="buffer (1 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">mutable_buffer</span> <span class="special">&</span> <span class="identifier">b</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload1.html" title="buffer (1 of 28 overloads)">more...</a></em></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload2.html" title="buffer (2 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">mutable_buffer</span> <span class="special">&</span> <span class="identifier">b</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload2.html" title="buffer (2 of 28 overloads)">more...</a></em></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload3.html" title="buffer (3 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">const_buffer</span> <span class="special">&</span> <span class="identifier">b</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload3.html" title="buffer (3 of 28 overloads)">more...</a></em></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload4.html" title="buffer (4 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">const_buffer</span> <span class="special">&</span> <span class="identifier">b</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload4.html" title="buffer (4 of 28 overloads)">more...</a></em></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload5.html" title="buffer (5 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">void</span> <span class="special">*</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload5.html" title="buffer (5 of 28 overloads)">more...</a></em></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload6.html" title="buffer (6 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="keyword">void</span> <span class="special">*</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload6.html" title="buffer (6 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload7.html" title="buffer (7 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">PodType</span> <span class="special">(&</span><span class="identifier">data</span><span class="special">)[</span><span class="identifier">N</span><span class="special">]);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload7.html" title="buffer (7 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload8.html" title="buffer (8 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">PodType</span> <span class="special">(&</span><span class="identifier">data</span><span class="special">)[</span><span class="identifier">N</span><span class="special">],</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload8.html" title="buffer (8 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload9.html" title="buffer (9 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">PodType</span> <span class="special">(&</span><span class="identifier">data</span><span class="special">)[</span><span class="identifier">N</span><span class="special">]);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload9.html" title="buffer (9 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload10.html" title="buffer (10 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">PodType</span> <span class="special">(&</span><span class="identifier">data</span><span class="special">)[</span><span class="identifier">N</span><span class="special">],</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload10.html" title="buffer (10 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload11.html" title="buffer (11 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload11.html" title="buffer (11 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload12.html" title="buffer (12 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload12.html" title="buffer (12 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload13.html" title="buffer (13 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="keyword">const</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload13.html" title="buffer (13 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload14.html" title="buffer (14 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="keyword">const</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload14.html" title="buffer (14 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload15.html" title="buffer (15 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload15.html" title="buffer (15 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload16.html" title="buffer (16 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload16.html" title="buffer (16 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload17.html" title="buffer (17 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload17.html" title="buffer (17 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload18.html" title="buffer (18 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload18.html" title="buffer (18 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload19.html" title="buffer (19 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="keyword">const</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload19.html" title="buffer (19 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload20.html" title="buffer (20 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="keyword">const</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload20.html" title="buffer (20 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload21.html" title="buffer (21 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload21.html" title="buffer (21 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">N</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload22.html" title="buffer (22 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">N</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload22.html" title="buffer (22 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload23.html" title="buffer (23 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload23.html" title="buffer (23 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">></span> <span class="identifier">mutable_buffers_1</span> <a class="link" href="buffer/overload24.html" title="buffer (24 of 28 overloads)">buffer</a><span class="special">(</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload24.html" title="buffer (24 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload25.html" title="buffer (25 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload25.html" title="buffer (25 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload26.html" title="buffer (26 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span> <span class="identifier">PodType</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload26.html" title="buffer (26 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">Elem</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload27.html" title="buffer (27 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">basic_string</span><span class="special"><</span> <span class="identifier">Elem</span><span class="special">,</span> <span class="identifier">Traits</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload27.html" title="buffer (27 of 28 overloads)">more...</a></em></span> <span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <span class="identifier">Elem</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Traits</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">></span> <span class="identifier">const_buffers_1</span> <a class="link" href="buffer/overload28.html" title="buffer (28 of 28 overloads)">buffer</a><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">basic_string</span><span class="special"><</span> <span class="identifier">Elem</span><span class="special">,</span> <span class="identifier">Traits</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">data</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_size_in_bytes</span><span class="special">);</span> <span class="emphasis"><em>» <a class="link" href="buffer/overload28.html" title="buffer (28 of 28 overloads)">more...</a></em></span> </pre> <p> A buffer object represents a contiguous region of memory as a 2-tuple consisting of a pointer and size in bytes. A tuple of the form <code class="computeroutput"><span class="special">{</span><span class="keyword">void</span><span class="special">*,</span> <span class="identifier">size_t</span><span class="special">}</span></code> specifies a mutable (modifiable) region of memory. Similarly, a tuple of the form <code class="computeroutput"><span class="special">{</span><span class="keyword">const</span> <span class="keyword">void</span><span class="special">*,</span> <span class="identifier">size_t</span><span class="special">}</span></code> specifies a const (non-modifiable) region of memory. These two forms correspond to the classes <a class="link" href="mutable_buffer.html" title="mutable_buffer"><code class="computeroutput"><span class="identifier">mutable_buffer</span></code></a> and <a class="link" href="const_buffer.html" title="const_buffer"><code class="computeroutput"><span class="identifier">const_buffer</span></code></a>, respectively. To mirror C++'s conversion rules, a <a class="link" href="mutable_buffer.html" title="mutable_buffer"><code class="computeroutput"><span class="identifier">mutable_buffer</span></code></a> is implicitly convertible to a <a class="link" href="const_buffer.html" title="const_buffer"><code class="computeroutput"><span class="identifier">const_buffer</span></code></a>, and the opposite conversion is not permitted. </p> <p> The simplest use case involves reading or writing a single buffer of a specified size: </p> <pre class="programlisting"><span class="identifier">sock</span><span class="special">.</span><span class="identifier">send</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</span><span class="special">,</span> <span class="identifier">size</span><span class="special">));</span> </pre> <p> In the above example, the return value of <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span></code> meets the requirements of the ConstBufferSequence concept so that it may be directly passed to the socket's write function. A buffer created for modifiable memory also meets the requirements of the MutableBufferSequence concept. </p> <p> An individual buffer may be created from a builtin array, std::vector, std::array or boost::array of POD elements. This helps prevent buffer overruns by automatically determining the size of the buffer: </p> <pre class="programlisting"><span class="keyword">char</span> <span class="identifier">d1</span><span class="special">[</span><span class="number">128</span><span class="special">];</span> <span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span> <span class="special">=</span> <span class="identifier">sock</span><span class="special">.</span><span class="identifier">receive</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d1</span><span class="special">));</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">char</span><span class="special">></span> <span class="identifier">d2</span><span class="special">(</span><span class="number">128</span><span class="special">);</span> <span class="identifier">bytes_transferred</span> <span class="special">=</span> <span class="identifier">sock</span><span class="special">.</span><span class="identifier">receive</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d2</span><span class="special">));</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="number">128</span><span class="special">></span> <span class="identifier">d3</span><span class="special">;</span> <span class="identifier">bytes_transferred</span> <span class="special">=</span> <span class="identifier">sock</span><span class="special">.</span><span class="identifier">receive</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d3</span><span class="special">));</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="number">128</span><span class="special">></span> <span class="identifier">d4</span><span class="special">;</span> <span class="identifier">bytes_transferred</span> <span class="special">=</span> <span class="identifier">sock</span><span class="special">.</span><span class="identifier">receive</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d4</span><span class="special">));</span> </pre> <p> In all three cases above, the buffers created are exactly 128 bytes long. Note that a vector is <span class="emphasis"><em>never</em></span> automatically resized when creating or using a buffer. The buffer size is determined using the vector's <code class="computeroutput"><span class="identifier">size</span><span class="special">()</span></code> member function, and not its capacity. </p> <h5> <a name="boost_asio.reference.buffer.h0"></a> <span class="phrase"><a name="boost_asio.reference.buffer.accessing_buffer_contents"></a></span><a class="link" href="buffer.html#boost_asio.reference.buffer.accessing_buffer_contents">Accessing Buffer Contents</a> </h5> <p> The contents of a buffer may be accessed using the <a class="link" href="buffer_size.html" title="buffer_size"><code class="computeroutput"><span class="identifier">buffer_size</span></code></a> and <a class="link" href="buffer_cast.html" title="buffer_cast"><code class="computeroutput"><span class="identifier">buffer_cast</span></code></a> functions: </p> <pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">mutable_buffer</span> <span class="identifier">b1</span> <span class="special">=</span> <span class="special">...;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">s1</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer_size</span><span class="special">(</span><span class="identifier">b1</span><span class="special">);</span> <span class="keyword">unsigned</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">p1</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer_cast</span><span class="special"><</span><span class="keyword">unsigned</span> <span class="keyword">char</span><span class="special">*>(</span><span class="identifier">b1</span><span class="special">);</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">const_buffer</span> <span class="identifier">b2</span> <span class="special">=</span> <span class="special">...;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">s2</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer_size</span><span class="special">(</span><span class="identifier">b2</span><span class="special">);</span> <span class="keyword">const</span> <span class="keyword">void</span><span class="special">*</span> <span class="identifier">p2</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer_cast</span><span class="special"><</span><span class="keyword">const</span> <span class="keyword">void</span><span class="special">*>(</span><span class="identifier">b2</span><span class="special">);</span> </pre> <p> The <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer_cast</span></code> function permits violations of type safety, so uses of it in application code should be carefully considered. </p> <p> For convenience, the <a class="link" href="buffer_size.html" title="buffer_size"><code class="computeroutput"><span class="identifier">buffer_size</span></code></a> function also works on buffer sequences (that is, types meeting the ConstBufferSequence or MutableBufferSequence type requirements). In this case, the function returns the total size of all buffers in the sequence. </p> <h5> <a name="boost_asio.reference.buffer.h1"></a> <span class="phrase"><a name="boost_asio.reference.buffer.buffer_copying"></a></span><a class="link" href="buffer.html#boost_asio.reference.buffer.buffer_copying">Buffer Copying</a> </h5> <p> The <a class="link" href="buffer_copy.html" title="buffer_copy"><code class="computeroutput"><span class="identifier">buffer_copy</span></code></a> function may be used to copy raw bytes between individual buffers and buffer sequences. </p> <p> In particular, when used with the <a class="link" href="buffer_size.html" title="buffer_size"><code class="computeroutput"><span class="identifier">buffer_size</span></code></a> , the <a class="link" href="buffer_copy.html" title="buffer_copy"><code class="computeroutput"><span class="identifier">buffer_copy</span></code></a> function can be used to linearise a sequence of buffers. For example: </p> <pre class="programlisting"><span class="identifier">vector</span><span class="special"><</span><span class="identifier">const_buffer</span><span class="special">></span> <span class="identifier">buffers</span> <span class="special">=</span> <span class="special">...;</span> <span class="identifier">vector</span><span class="special"><</span><span class="keyword">unsigned</span> <span class="keyword">char</span><span class="special">></span> <span class="identifier">data</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer_size</span><span class="special">(</span><span class="identifier">buffers</span><span class="special">));</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</span><span class="special">),</span> <span class="identifier">buffers</span><span class="special">);</span> </pre> <p> Note that <a class="link" href="buffer_copy.html" title="buffer_copy"><code class="computeroutput"><span class="identifier">buffer_copy</span></code></a> is implemented in terms of <code class="computeroutput"><span class="identifier">memcpy</span></code>, and consequently it cannot be used to copy between overlapping memory regions. </p> <h5> <a name="boost_asio.reference.buffer.h2"></a> <span class="phrase"><a name="boost_asio.reference.buffer.buffer_invalidation"></a></span><a class="link" href="buffer.html#boost_asio.reference.buffer.buffer_invalidation">Buffer Invalidation</a> </h5> <p> A buffer object does not have any ownership of the memory it refers to. It is the responsibility of the application to ensure the memory region remains valid until it is no longer required for an I/O operation. When the memory is no longer available, the buffer is said to have been invalidated. </p> <p> For the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span></code> overloads that accept an argument of type std::vector, the buffer objects returned are invalidated by any vector operation that also invalidates all references, pointers and iterators referring to the elements in the sequence (C++ Std, 23.2.4) </p> <p> For the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span></code> overloads that accept an argument of type std::basic_string, the buffer objects returned are invalidated according to the rules defined for invalidation of references, pointers and iterators referring to elements of the sequence (C++ Std, 21.3). </p> <h5> <a name="boost_asio.reference.buffer.h3"></a> <span class="phrase"><a name="boost_asio.reference.buffer.buffer_arithmetic"></a></span><a class="link" href="buffer.html#boost_asio.reference.buffer.buffer_arithmetic">Buffer Arithmetic</a> </h5> <p> Buffer objects may be manipulated using simple arithmetic in a safe way which helps prevent buffer overruns. Consider an array initialised as follows: </p> <pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="number">6</span><span class="special">></span> <span class="identifier">a</span> <span class="special">=</span> <span class="special">{</span> <span class="char">'a'</span><span class="special">,</span> <span class="char">'b'</span><span class="special">,</span> <span class="char">'c'</span><span class="special">,</span> <span class="char">'d'</span><span class="special">,</span> <span class="char">'e'</span> <span class="special">};</span> </pre> <p> A buffer object <code class="computeroutput"><span class="identifier">b1</span></code> created using: </p> <pre class="programlisting"><span class="identifier">b1</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">a</span><span class="special">);</span> </pre> <p> represents the entire array, <code class="computeroutput"><span class="special">{</span> <span class="char">'a'</span><span class="special">,</span> <span class="char">'b'</span><span class="special">,</span> <span class="char">'c'</span><span class="special">,</span> <span class="char">'d'</span><span class="special">,</span> <span class="char">'e'</span> <span class="special">}</span></code>. An optional second argument to the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span></code> function may be used to limit the size, in bytes, of the buffer: </p> <pre class="programlisting"><span class="identifier">b2</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">a</span><span class="special">,</span> <span class="number">3</span><span class="special">);</span> </pre> <p> such that <code class="computeroutput"><span class="identifier">b2</span></code> represents the data <code class="computeroutput"><span class="special">{</span> <span class="char">'a'</span><span class="special">,</span> <span class="char">'b'</span><span class="special">,</span> <span class="char">'c'</span> <span class="special">}</span></code>. Even if the size argument exceeds the actual size of the array, the size of the buffer object created will be limited to the array size. </p> <p> An offset may be applied to an existing buffer to create a new one: </p> <pre class="programlisting"><span class="identifier">b3</span> <span class="special">=</span> <span class="identifier">b1</span> <span class="special">+</span> <span class="number">2</span><span class="special">;</span> </pre> <p> where <code class="computeroutput"><span class="identifier">b3</span></code> will set to represent <code class="computeroutput"><span class="special">{</span> <span class="char">'c'</span><span class="special">,</span> <span class="char">'d'</span><span class="special">,</span> <span class="char">'e'</span> <span class="special">}</span></code>. If the offset exceeds the size of the existing buffer, the newly created buffer will be empty. </p> <p> Both an offset and size may be specified to create a buffer that corresponds to a specific range of bytes within an existing buffer: </p> <pre class="programlisting"><span class="identifier">b4</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">b1</span> <span class="special">+</span> <span class="number">1</span><span class="special">,</span> <span class="number">3</span><span class="special">);</span> </pre> <p> so that <code class="computeroutput"><span class="identifier">b4</span></code> will refer to the bytes <code class="computeroutput"><span class="special">{</span> <span class="char">'b'</span><span class="special">,</span> <span class="char">'c'</span><span class="special">,</span> <span class="char">'d'</span> <span class="special">}</span></code>. </p> <h5> <a name="boost_asio.reference.buffer.h4"></a> <span class="phrase"><a name="boost_asio.reference.buffer.buffers_and_scatter_gather_i_o"></a></span><a class="link" href="buffer.html#boost_asio.reference.buffer.buffers_and_scatter_gather_i_o">Buffers and Scatter-Gather I/O</a> </h5> <p> To read or write using multiple buffers (i.e. scatter-gather I/O), multiple buffer objects may be assigned into a container that supports the MutableBufferSequence (for read) or ConstBufferSequence (for write) concepts: </p> <pre class="programlisting"><span class="keyword">char</span> <span class="identifier">d1</span><span class="special">[</span><span class="number">128</span><span class="special">];</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="keyword">char</span><span class="special">></span> <span class="identifier">d2</span><span class="special">(</span><span class="number">128</span><span class="special">);</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="keyword">char</span><span class="special">,</span> <span class="number">128</span><span class="special">></span> <span class="identifier">d3</span><span class="special">;</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">array</span><span class="special"><</span><span class="identifier">mutable_buffer</span><span class="special">,</span> <span class="number">3</span><span class="special">></span> <span class="identifier">bufs1</span> <span class="special">=</span> <span class="special">{</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d1</span><span class="special">),</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d2</span><span class="special">),</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d3</span><span class="special">)</span> <span class="special">};</span> <span class="identifier">bytes_transferred</span> <span class="special">=</span> <span class="identifier">sock</span><span class="special">.</span><span class="identifier">receive</span><span class="special">(</span><span class="identifier">bufs1</span><span class="special">);</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special"><</span><span class="identifier">const_buffer</span><span class="special">></span> <span class="identifier">bufs2</span><span class="special">;</span> <span class="identifier">bufs2</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d1</span><span class="special">));</span> <span class="identifier">bufs2</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d2</span><span class="special">));</span> <span class="identifier">bufs2</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">d3</span><span class="special">));</span> <span class="identifier">bytes_transferred</span> <span class="special">=</span> <span class="identifier">sock</span><span class="special">.</span><span class="identifier">send</span><span class="special">(</span><span class="identifier">bufs2</span><span class="special">);</span> </pre> <h5> <a name="boost_asio.reference.buffer.h5"></a> <span class="phrase"><a name="boost_asio.reference.buffer.requirements"></a></span><a class="link" href="buffer.html#boost_asio.reference.buffer.requirements">Requirements</a> </h5> <p> <span class="emphasis"><em>Header: </em></span><code class="literal">boost/asio/buffer.hpp</code> </p> <p> <span class="emphasis"><em>Convenience header: </em></span><code class="literal">boost/asio.hpp</code> </p> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2003-2015 Christopher M. Kohlhoff<p> Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) </p> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="basic_yield_context/operator_lb__rb_.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="buffer/overload1.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>