right operand of comma operator has no effect std::cout
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/5665611/why-does-this-code-produce-a-warning-referring-to-the-comma-operator">Why does this code produce a warning referring to the comma operator?</a>  </p>
</blockquote>



<p>Why i get this warning while trying to compile this example in gcc?</p>

<pre><code>#include &lt;iostream&gt;

int main()
{
   std::cout &lt;&lt; "str" &lt; 0;
}
</code></pre>

<blockquote>
  <p>warning: right operand of comma operator has no effect
  [-Wunused-value]</p>
</blockquote>
