title: How can I print out all possible letter combinations a given phone number can represent?
body: <p>I just tried for my first programming interview and one of the questions was to write a program that given a 7 digit telephone number, could print all possible combinations of letters that each number could represent.</p>
  
  <p>A second part of the question was like what about if this would have been a 12 digit international number?  How would that effect your design.</p>
  
  <p>I don't have the code that I wrote in the interview, but I got the impression he wasn't happy with it.<br>
  What is the best way to do this?</p>