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4.6.3 A simple addstr example

#!/usr/bin/guile
!#

(use-modules (ncurses curses)
             (srfi srfi-1))

(define stdscr (initscr))

(let* ((mesg "Just a string")
       (len (string-length mesg))
       (siz (getmaxyx stdscr))
       (row (first siz))
       (col (second siz)))

  ;; Print the message centered in the window
  (move stdscr
        (round (/ row 2))
        (round (/ (- col len) 2)))
  (addstr stdscr mesg)

  ;; Use "format" to generate a message, and then print it
  (addstr stdscr
          (format #f "This screen has ~a rows and ~a columns ~%"
                  row col)
          #:y (- row 2)
          #:x 0)

  (addstr stdscr "Try resizing your window (if possible) ")
  (addstr stdscr "and then run this program again")
  (refresh stdscr)

  ;; Wait for a keypress
  (getch stdscr)
  (endwin))

The above program demonstrates how easy it is to combine addstr and move to print at a specific location on the screen. It also shows how to use the equivalent key parameters #:y and #:x. They do exactly the same thing. It also shows how (format #f …) can be used in conjunction with addstr to do formatted output.

The example introduces the new function getmaxyx. It gives the number of columns and the number of rows in a given window. getmaxyx does this by returning a list of two elements, y and x.