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<title>read_until (3 of 8 overloads)</title>
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<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="boost_asio.reference.read_until.overload3"></a><a class="link" href="overload3.html" title="read_until (3 of 8 overloads)">read_until
(3 of 8 overloads)</a>
</h4></div></div></div>
<p>
Read data into a streambuf until it contains a specified delimiter.
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span>
<span class="keyword">typename</span> <a class="link" href="../SyncReadStream.html" title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a><span class="special">,</span>
<span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">></span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">read_until</span><span class="special">(</span>
<span class="identifier">SyncReadStream</span> <span class="special">&</span> <span class="identifier">s</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">basic_streambuf</span><span class="special"><</span> <span class="identifier">Allocator</span> <span class="special">></span> <span class="special">&</span> <span class="identifier">b</span><span class="special">,</span>
<span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="special">&</span> <span class="identifier">delim</span><span class="special">);</span>
</pre>
<p>
This function is used to read data into the specified streambuf until the
streambuf's get area contains the specified delimiter. The call will block
until one of the following conditions is true:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
The get area of the streambuf contains the specified delimiter.
</li>
<li class="listitem">
An error occurred.
</li>
</ul></div>
<p>
This operation is implemented in terms of zero or more calls to the stream's
read_some function. If the streambuf's get area already contains the delimiter,
the function returns immediately.
</p>
<h6>
<a name="boost_asio.reference.read_until.overload3.h0"></a>
<span class="phrase"><a name="boost_asio.reference.read_until.overload3.parameters"></a></span><a class="link" href="overload3.html#boost_asio.reference.read_until.overload3.parameters">Parameters</a>
</h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">s</span></dt>
<dd><p>
The stream from which the data is to be read. The type must support
the SyncReadStream concept.
</p></dd>
<dt><span class="term">b</span></dt>
<dd><p>
A streambuf object into which the data will be read.
</p></dd>
<dt><span class="term">delim</span></dt>
<dd><p>
The delimiter string.
</p></dd>
</dl>
</div>
<h6>
<a name="boost_asio.reference.read_until.overload3.h1"></a>
<span class="phrase"><a name="boost_asio.reference.read_until.overload3.return_value"></a></span><a class="link" href="overload3.html#boost_asio.reference.read_until.overload3.return_value">Return
Value</a>
</h6>
<p>
The number of bytes in the streambuf's get area up to and including the
delimiter.
</p>
<h6>
<a name="boost_asio.reference.read_until.overload3.h2"></a>
<span class="phrase"><a name="boost_asio.reference.read_until.overload3.exceptions"></a></span><a class="link" href="overload3.html#boost_asio.reference.read_until.overload3.exceptions">Exceptions</a>
</h6>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">boost::system::system_error</span></dt>
<dd><p>
Thrown on failure.
</p></dd>
</dl>
</div>
<h6>
<a name="boost_asio.reference.read_until.overload3.h3"></a>
<span class="phrase"><a name="boost_asio.reference.read_until.overload3.remarks"></a></span><a class="link" href="overload3.html#boost_asio.reference.read_until.overload3.remarks">Remarks</a>
</h6>
<p>
After a successful read_until operation, the streambuf may contain additional
data beyond the delimiter. An application will typically leave that data
in the streambuf for a subsequent read_until operation to examine.
</p>
<h6>
<a name="boost_asio.reference.read_until.overload3.h4"></a>
<span class="phrase"><a name="boost_asio.reference.read_until.overload3.example"></a></span><a class="link" href="overload3.html#boost_asio.reference.read_until.overload3.example">Example</a>
</h6>
<p>
To read data into a streambuf until a newline is encountered:
</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">streambuf</span> <span class="identifier">b</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">read_until</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span class="identifier">b</span><span class="special">,</span> <span class="string">"\r\n"</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">istream</span> <span class="identifier">is</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">string</span> <span class="identifier">line</span><span class="special">;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">getline</span><span class="special">(</span><span class="identifier">is</span><span class="special">,</span> <span class="identifier">line</span><span class="special">);</span>
</pre>
<p>
After the <code class="computeroutput"><span class="identifier">read_until</span></code> operation
completes successfully, the buffer <code class="computeroutput"><span class="identifier">b</span></code>
contains the delimiter:
</p>
<pre class="programlisting"><span class="special">{</span> <span class="char">'a'</span><span class="special">,</span> <span class="char">'b'</span><span class="special">,</span> <span class="special">...,</span> <span class="char">'c'</span><span class="special">,</span> <span class="char">'\r'</span><span class="special">,</span> <span class="char">'\n'</span><span class="special">,</span> <span class="char">'d'</span><span class="special">,</span> <span class="char">'e'</span><span class="special">,</span> <span class="special">...</span> <span class="special">}</span>
</pre>
<p>
The call to <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">getline</span></code> then extracts the data up to
and including the delimiter, so that the string <code class="computeroutput"><span class="identifier">line</span></code>
contains:
</p>
<pre class="programlisting"><span class="special">{</span> <span class="char">'a'</span><span class="special">,</span> <span class="char">'b'</span><span class="special">,</span> <span class="special">...,</span> <span class="char">'c'</span><span class="special">,</span> <span class="char">'\r'</span><span class="special">,</span> <span class="char">'\n'</span> <span class="special">}</span>
</pre>
<p>
The remaining data is left in the buffer <code class="computeroutput"><span class="identifier">b</span></code>
as follows:
</p>
<pre class="programlisting"><span class="special">{</span> <span class="char">'d'</span><span class="special">,</span> <span class="char">'e'</span><span class="special">,</span> <span class="special">...</span> <span class="special">}</span>
</pre>
<p>
This data may be the start of a new line, to be extracted by a subsequent
<code class="computeroutput"><span class="identifier">read_until</span></code> operation.
</p>
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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>)
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