Guessed size and nullpointer

When i changed my code to accept more inputs for guessed i started to fail more and more tests. To clarify if my assumptions why i fail them are correct i need answers to following questions
(since i cant just post my full implementation):

  1. should we accept any input if the dictionary given is a nullpointer, no matter what the input is? this would imply that the returned word could be any size and include any chars( not only a-z).
    Or should we
  2. return a pointer of exactly size (k+1) not matter what.
    would a return of a pointer of size (k+2) be different if it is terminated at index k using a null point or a newline and index k+1 could be anything?
    or would a aray of any different size lead to imediate fail in the guess tests. should it be terminated with ā€˜\nā€™ or ā€˜\0ā€™ or does this not matter at all?