Question

I’m completely new to lisp programming. I need to write a program for a class that reads words out of an xml doc. Anyway, I wrote this function that takes an array (word) and a file stream (in). I want it to loop until it reaches a #\space in the stream while adding each collected character to the word. I then want the word returned. I’m sure I’m doing many things wrong, but here’s the method I have. I’m fairly certain that the return function at the end is completely out of place:

(defun get-string (in word)
  (loop for char = (read-char in nil)
      while (not (char= char #\space))
      do(vector-push-extend char word))
  (return word))

Now I have anther issue. The loop keeps on looking for characters after it finds a space and I get a bunch of nils. Also, I need to stop on newlines, but am not sure how to. I tied this, but it just reads every character.

(defun get-string (in word)
 (loop for char = (read-char in nil)
      while (not (or (char= char #\space)
                (char= char #\newline)))
    do(print char))
  word)

The print char is in there because I’m not very good at understanding the debugger and want to see what characters I’m reading.

Answer 1

word is a variable and a variable evaluates to its value. In a DEFUN body, the last expression’s value is returned. So the return around word is not needed, if you want to return the value of word.