查找用户输入字符串中接近，完全或不存在的字母

I am currently developing a small modified version of Hangman in Rails for children. The game starts by randomly generating a word from a text file and the user has to guess the word by entering a four letter word. Each word is the split by each character for example "r", "e", "a", "l" and returns a message on how they are to the word.I am currently developing a small modified vers