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<div class="titlepage"><div><div><h4 class="title">
<a name="boost_regex.ref.deprecated_interfaces.regex_split"></a><a class="link" href="regex_split.html" title="regex_split (deprecated)">
regex_split (deprecated)</a>
</h4></div></div></div>
<p>
The algorithm <a class="link" href="regex_split.html" title="regex_split (deprecated)"><code class="computeroutput"><span class="identifier">regex_split</span></code></a> has been deprecated
in favor of the iterator <a class="link" href="../regex_token_iterator.html" title="regex_token_iterator"><code class="computeroutput"><span class="identifier">regex_token_iterator</span></code></a> which has
a more flexible and powerful interface, as well as following the more usual
standard library "pull" rather than "push" semantics.
</p>
<p>
Code which uses <a class="link" href="regex_split.html" title="regex_split (deprecated)"><code class="computeroutput"><span class="identifier">regex_split</span></code></a> will continue to compile,
the following documentation is taken from a previous Boost.Regex version:
</p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">regex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
</pre>
<p>
Algorithm <a class="link" href="regex_split.html" title="regex_split (deprecated)"><code class="computeroutput"><span class="identifier">regex_split</span></code></a> performs a similar
operation to the perl split operation, and comes in three overloaded forms:
</p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">OutputIterator</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">charT</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Traits1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Alloc1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Traits2</span><span class="special">></span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">regex_split</span><span class="special">(</span><span class="identifier">OutputIterator</span> <span class="identifier">out</span><span class="special">,</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">basic_string</span><span class="special"><</span><span class="identifier">charT</span><span class="special">,</span> <span class="identifier">Traits1</span><span class="special">,</span> <span class="identifier">Alloc1</span><span class="special">>&</span> <span class="identifier">s</span><span class="special">,</span>
<span class="keyword">const</span> <span class="identifier">basic_regex</span><span class="special"><</span><span class="identifier">charT</span><span class="special">,</span> <span class="identifier">Traits2</span><span class="special">>&</span> <span class="identifier">e</span><span class="special">,</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">match_flag_type</span> <span class="identifier">flags</span><span class="special">,</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">max_split</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">OutputIterator</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">charT</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Traits1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Alloc1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Traits2</span><span class="special">></span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">regex_split</span><span class="special">(</span><span class="identifier">OutputIterator</span> <span class="identifier">out</span><span class="special">,</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">basic_string</span><span class="special"><</span><span class="identifier">charT</span><span class="special">,</span> <span class="identifier">Traits1</span><span class="special">,</span> <span class="identifier">Alloc1</span><span class="special">>&</span> <span class="identifier">s</span><span class="special">,</span>
<span class="keyword">const</span> <span class="identifier">basic_regex</span><span class="special"><</span><span class="identifier">charT</span><span class="special">,</span> <span class="identifier">Traits2</span><span class="special">>&</span> <span class="identifier">e</span><span class="special">,</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">match_flag_type</span> <span class="identifier">flags</span> <span class="special">=</span> <span class="identifier">match_default</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">OutputIterator</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">charT</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Traits1</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Alloc1</span><span class="special">></span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">regex_split</span><span class="special">(</span><span class="identifier">OutputIterator</span> <span class="identifier">out</span><span class="special">,</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">basic_string</span><span class="special"><</span><span class="identifier">charT</span><span class="special">,</span> <span class="identifier">Traits1</span><span class="special">,</span> <span class="identifier">Alloc1</span><span class="special">>&</span> <span class="identifier">s</span><span class="special">);</span>
</pre>
<p>
<span class="bold"><strong>Effects</strong></span>: Each version of the algorithm
takes an output-iterator for output, and a string for input. If the expression
contains no marked sub-expressions, then the algorithm writes one string
onto the output-iterator for each section of input that does not match
the expression. If the expression does contain marked sub-expressions,
then each time a match is found, one string for each marked sub-expression
will be written to the output-iterator. No more than max_split strings
will be written to the output-iterator. Before returning, all the input
processed will be deleted from the string <span class="emphasis"><em>s</em></span> (if <span class="emphasis"><em>max_split</em></span>
is not reached then all of <span class="emphasis"><em>s</em></span> will be deleted). Returns
the number of strings written to the output-iterator. If the parameter
<span class="emphasis"><em>max_split</em></span> is not specified then it defaults to <code class="computeroutput"><span class="identifier">UINT_MAX</span></code>. If no expression is specified,
then it defaults to "\s+", and splitting occurs on whitespace.
</p>
<p>
<span class="bold"><strong>Throws</strong></span>: <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">runtime_error</span></code>
if the complexity of matching the expression against an N character string
begins to exceed O(N<sup>2</sup>), or if the program runs out of stack space while
matching the expression (if Boost.Regex is configured in recursive mode),
or if the matcher exhausts its permitted memory allocation (if Boost.Regex
is configured in non-recursive mode).
</p>
<p>
<span class="bold"><strong>Example</strong></span>: the following function will split
the input string into a series of tokens, and remove each token from the
string <span class="emphasis"><em>s</em></span>:
</p>
<pre class="programlisting"><span class="keyword">unsigned</span> <span class="identifier">tokenise</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">>&</span> <span class="identifier">l</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&</span> <span class="identifier">s</span><span class="special">)</span>
<span class="special">{</span>
<span class="keyword">return</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">regex_split</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">back_inserter</span><span class="special">(</span><span class="identifier">l</span><span class="special">),</span> <span class="identifier">s</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
Example: the following short program will extract all of the URL's from
a html file, and print them out to cout:
</p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">list</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">fstream</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">regex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">regex</span> <span class="identifier">e</span><span class="special">(</span><span class="string">"<\\s*A\\s+[^>]*href\\s*=\\s*\"([^\"]*)\""</span><span class="special">,</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">regbase</span><span class="special">::</span><span class="identifier">normal</span> <span class="special">|</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">regbase</span><span class="special">::</span><span class="identifier">icase</span><span class="special">);</span>
<span class="keyword">void</span> <span class="identifier">load_file</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&</span> <span class="identifier">s</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">istream</span><span class="special">&</span> <span class="identifier">is</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">s</span><span class="special">.</span><span class="identifier">erase</span><span class="special">();</span>
<span class="comment">//
</span> <span class="comment">// attempt to grow string buffer to match file size,
</span> <span class="comment">// this doesn't always work...
</span> <span class="identifier">s</span><span class="special">.</span><span class="identifier">reserve</span><span class="special">(</span><span class="identifier">is</span><span class="special">.</span><span class="identifier">rdbuf</span><span class="special">()-&</span><span class="identifier">gtin_avail</span><span class="special">());</span>
<span class="keyword">char</span> <span class="identifier">c</span><span class="special">;</span>
<span class="keyword">while</span><span class="special">(</span><span class="identifier">is</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="identifier">c</span><span class="special">))</span>
<span class="special">{</span>
<span class="comment">// use logarithmic growth stategy, in case
</span> <span class="comment">// in_avail (above) returned zero:
</span> <span class="keyword">if</span><span class="special">(</span><span class="identifier">s</span><span class="special">.</span><span class="identifier">capacity</span><span class="special">()</span> <span class="special">==</span> <span class="identifier">s</span><span class="special">.</span><span class="identifier">size</span><span class="special">())</span>
<span class="identifier">s</span><span class="special">.</span><span class="identifier">reserve</span><span class="special">(</span><span class="identifier">s</span><span class="special">.</span><span class="identifier">capacity</span><span class="special">()</span> <span class="special">*</span> <span class="number">3</span><span class="special">);</span>
<span class="identifier">s</span><span class="special">.</span><span class="identifier">append</span><span class="special">(</span><span class="number">1</span><span class="special">,</span> <span class="identifier">c</span><span class="special">);</span>
<span class="special">}</span>
<span class="special">}</span>
<span class="keyword">int</span> <span class="identifier">main</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">argc</span><span class="special">,</span> <span class="keyword">char</span><span class="special">**</span> <span class="identifier">argv</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">s</span><span class="special">;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">></span> <span class="identifier">l</span><span class="special">;</span>
<span class="keyword">for</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">1</span><span class="special">;</span> <span class="identifier">i</span> <span class="special"><</span> <span class="identifier">argc</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Findings URL's in "</span> <span class="special"><<</span> <span class="identifier">argv</span><span class="special">[</span><span class="identifier">i</span><span class="special">]</span> <span class="special"><<</span> <span class="string">":"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="identifier">s</span><span class="special">.</span><span class="identifier">erase</span><span class="special">();</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">ifstream</span> <span class="identifier">is</span><span class="special">(</span><span class="identifier">argv</span><span class="special">[</span><span class="identifier">i</span><span class="special">]);</span>
<span class="identifier">load_file</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span class="identifier">is</span><span class="special">);</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">regex_split</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">back_inserter</span><span class="special">(</span><span class="identifier">l</span><span class="special">),</span> <span class="identifier">s</span><span class="special">,</span> <span class="identifier">e</span><span class="special">);</span>
<span class="keyword">while</span><span class="special">(</span><span class="identifier">l</span><span class="special">.</span><span class="identifier">size</span><span class="special">())</span>
<span class="special">{</span>
<span class="identifier">s</span> <span class="special">=</span> <span class="special">*(</span><span class="identifier">l</span><span class="special">.</span><span class="identifier">begin</span><span class="special">());</span>
<span class="identifier">l</span><span class="special">.</span><span class="identifier">pop_front</span><span class="special">();</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">s</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="special">}</span>
<span class="special">}</span>
<span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
<span class="special">}</span>
</pre>
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<td align="right"><div class="copyright-footer">Copyright © 1998 -2007 John Maddock<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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