title: php generate all possible values of characters
body: <p>I would like a function to generate all possible combination of alphabets. The only parameter the function would need is the number of characters. So for instance if I pass '2', it'll generate:</p>
  
  <pre><code>aa
  ab
  ac
  ad
  ae
  ..
  ..
  zz
  </code></pre>
  
  <p>If I pass 3, it'll generate:</p>
  
  <pre><code>aaa
  aab
  ...
  ...
  aaz
  ...
  zzz
  </code></pre>
  
  <p>And so on if I pass 4, etc. Thank you in advance!</p>