span><span class="special">::</span><span class="identifier">string</span> <span class="identifier">str</span><span class="special">;</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">format</span> <span class="identifier">int_format</span><span class="special">(</span><span class="string">"%d"</span><span class="special">);</span>
<span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span