he operation that you want to trace through, like so:</p>

<p><img src="img/breakpoint.png" alt="breakpoint on line that has call to lettersOnly" width="70%" /></p>

<p>Now run the tests while using the debugger. When you hit the breakpoint, single step through the call to <code class="language-c++ highlighter-rouge"><span class="n">lettersOnly</span></code> while watching the debugger's variables pane to see how the values are changing. This "step-and-watch" approach is the same as you used in the <a href=