<span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">bm</span><span class="special">.</span><span class="identifier">right</span><span class="special">.</span><span class="identifier">at</span><span class="special">(</span> <span class="string">"Modern C++ Design"</span> <span class="special">);</span>
</pre>
<p>
      </p>
<p>
        Suppose now that we want to store abstract of each book. We have two options:
      </p>
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