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Casting a character to a string in common lisp

Casting a character to a string in common lisp

(OP)
I am very new to common lisp so sorry if this is a newbie question.  I am trying to write a function that take a stream read from a file as input and adds all the character that are not /s to a string.  So my input will look something like this:  
4//4 3//3 2//2 1//1
and here is the method I made:  
(defun READ-INT(String)
  (let ((Number  ""))
    (loop
      (let((num-char ""))
      (setf num-char (read-char String)) ; ))))

        (if (equal num-char #\/) (return-from read-int Number)
          (setf Number (concatenate 'string Number num-char)))
        (print Number)
        (print num-char)
        ))) )
The String parameter is a stream that I read in form a file, I initialize Number and num-char to empty strings then setf num-char to be the first char read from the stream.  Then if the char is a / I return what I have so far and if not I add try and add the character to the Number string but it gives this error
"Error: value #\4 is not of the expected type SEQUENCE."
So I think my problem is that the character 4 is not a string so it can't perform the concatenate.  Is there an easy way to cast the char to a string?  I found something called char-to-string on an emacs lisp page but it does not seem to be in the Clozure cl implementation.  Is there something similar in Clozure?  Thanks.   

RE: Casting a character to a string in common lisp

Hi ender2012,

I don't understand good what you exactly want to do.
When your input is e.g. this

CODE

4//4 3//3 2//2 1//1
and you say, that it should add "all the character that are not /s to a string", then should be this your ouput ?

CODE

4/ 3/ 2/ 1/
Or something else?
 

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