A file handling example

Lisp files.lisp

(defparameter *line* nil "This is a global variable")

;;; an example
(with-open-file (file "/tmp/myfile.txt" :direction :input)
  (loop
    ;; gets a line from the file
    (setf *line* (read-line file nil))
    (if *line*
	;; print the lines stored in the text file
	(format t "~% ~a ~%" *line*)
	;; End Of File
	(return t))))

;;; :direction :input => meaning you want to read from the file
;;; :direction :output (meaning you want to write to the file)
;;; :if-exists :supersede => meaning that the new file will replace the old one)
;;; :if-exists :append => opens the file to append data to it


(defun load-data (filename)
  ;; :direction :input => meaning you want to read from the file
  (with-open-file (file filename :direction :input)
    (loop
      ;; gets a line from the file
      (setf *line* (read-line file nil))
      (if *line*
	  ;; print the lines stored in the text file
	  (format t "~a ~%" *line*)
	  ;; Enf Of File
	  (return t)))))

(defun store-data (filename data)
  ;; :direction :output (meaning you want to write to the file)
  ;; :if-exists :append => opens the file to append data to it
  (with-open-file (file filename :direction :output :if-exists :append)
    ;; writes a line in the file
    (write-line data file))
  (format t "The file was written"))