header/cctype" title="Documentation for cctype"><code class="language-c++ highlighter-rouge"><span class="n">isalpha</span></code></a> will report whether a character is alphabetic (i.e. is a letter).  Here is a starting point (provided for you in <code class="language-c++ highlighter-rouge"><span class="n">soundex</span><span class="p">.</span><span class="n">cpp</span></code>):</p>

<div class="language-c++ highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="c1">// WARNING: