How to convert an alphanumeric phone number to digits

Question

UPDATE:

The final version of my utility looks like this:

StringBuilder b = new StringBuilder();

for(char c : inLetters.toLowerCase(         


        

Answer 1

If you run this 10^9 times in a tight loop and ctrl-break it a few times, my bet is that nearly every time it will be deep in the string class trying to accomplish one of those innocent-looking "+=" operators.