Script Library: 1218 scripts
 

calculator-tutorial.r

REBOL [ title: "calculator" date: 28-feb-2009 file: %calculator-tutorial.r purpose: { A little GUI calculator example, with printout. Taken from the tutorial at http://musiclessonz.com/rebol_tutorial.html } ] prev-val: cur-val: 0 cur-eval: "+" display-flag: false print "0" view center-face layout/tight [ size 300x350 space 0x0 across display: field 300x50 font-size 28 "0" return style butn button 100x50 [ if display-flag = true [display/text: "" display-flag: false] if display/text = "0" [display/text: ""] display/text: rejoin [display/text value] show display cur-val: display/text ] style eval button 100x50 brown font-size 13 [ prev-val: cur-val display/text: "" show display cur-eval: value ] butn "1" butn "2" butn "3" return butn "4" butn "5" butn "6" return butn "7" butn "8" butn "9" return butn "0" butn "." eval "+" return eval "-" eval "*" eval "/" return button 300x50 gray font-size 16 "=" [ if display-flag <> true [ if ((cur-eval = "/") and (cur-val = "0")) [ alert "Division by 0 is not allowed." break ] prin rejoin [prev-val " " cur-eval " " cur-val " = "] print display/text: cur-val: do rejoin [ prev-val " " cur-eval " " cur-val ] show display display-flag: true ] ] ]
halt ;; to terminate script if DO'ne from webpage