The largest forum on the web, called postcount++ decided to make a new forum game. In this game, the goal is to post the word, but the word has to have one letter added, removed, or changed. Your boss wanted you to write a program which gets the word, and the UNIX dictionary, as you work for company who has more intelligent forum with more intelligent forum games, and wants to destroy the competition (hey, it's your boss, don't discuss with him, you get lots of cash from your job anyway).
Your program will get two arguments, the word, and the dictionary. Because the user managing the program (yes, an user, your company doesn't have resources to run bots) is not perfect, you should normalize the case in both. The words in dictionary may have ASCII letters (both upper-case and lower-case, but it should be ignored during comparison), dashes, apostrophes, and non-consecutive spaces in middle. They won't be longer than 78 characters. You have to output list of words that would be accepted in the game, to break the fun of people who think of words manually.
This is an example of your expected program, checking for similar words to
> ./similar golf /usr/share/dict/words Goff Wolf gold golfs goof gulf wolf
/usr/share/dict/words is a list of words, with line break after each. You can easily read that with fgets(), for example.
The company you work in doesn't have much punch cards (yes, it's 2014, and they still use punch cards), so don't waste them. Write as short program as possible. Oh, and you were asked to not use built-in or external implementations of Levenshtein distance or any similar algorithm. Something about Not Invented Here or backdoors that apparently the vendor inserted into the language (you don't have proof of those, but don't discuss with your boss). So if you want distance, you will have to implement it yourself.
You are free to use any language. Even with punch cards, the company has the access to most modern of programming languages, such as
Cobol Ruby or Haskell or whatever you want. They even have GolfScript, if you think it's good for string manipulation (I don't know, perhaps...).
The winner gets 15 reputation points from me, and probably lots of other points from the community. The other good answers will get 10 points, and points from community as well. You heard that points are worthless, but most likely that they will replace dolars in 2050. That wasn't confirmed however, but it's good idea to get points anyway.