TESTING
- Easy cases
- Edge cases - smallest, largest, shortest, longest (or long enough)
  print_integer(INT_MIN, …, …)  // smallest n
  print_integer(INT_MAX, …, …)  // largest  n
  print_integer(…, 2, …)        // smallest radix
  print_integer(…, 36, …)       // largest radix
  print_integer(…, …, "")       // shortest prefix
  print_integer(…, …, "abc")    // longest (or long enough) prefix
- Corner cases - values that are at/near a point where behavior changes
  Look for if/while/for statements and ask what value makes them triggered (i.e., go into
  body of if/loop, and what value(s) makes them skipped.  Try values at and adjacent to
  that point.
  - print_integer( 0, …, …)
  - print_integer( 1, …, …)
  - print_integer(-1, …, …)
  - print_integer(-1, …, …)
  - print_integer(…,  9, …)
  - print_integer(…, 10, …)
  - print_integer(…, 11, …)
- Special cases -- Look for careful wording in the specification, or mentions of exceptions.

OK to copy/adapt anything in this file for use in your HW02 code.

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Ctrl-C to get out of infinite loop.