 <blockquote> <p>What is the difference between the three, in terms of readability and performance?</p> </blockquote> <p>There should be no difference in performance no matter which form you use.</p> <p>As for readability, it's a matter of opinion. I would prefer to use </p> <pre><code>(*this)[i]; </code></pre> <p>but I wouldn't complain if someone used one of the other forms.</p> <blockquote> <p>Which is the "correct" way of invoking the operator?</p> </blockquote> <p>All are correct - syntactically as well as semantically.</p>