</a></span><a class="link" href="basic_extended.html#boost_regex.syntax.basic_extended.alternation">Alternation</a>
      </h5>
<p>
        The <code class="computeroutput"><span class="special">|</span></code> operator will match either
        of its arguments, so for example: <code class="computeroutput"><span class="identifier">abc</span><span class="special">|</span><span class="identifier">def</span></code> will
        match either "abc" or "def".
      </p>
<p>
        Parenthesis can be used to gro