Racket中使用GUI创建简单计算器

本示例演示如何使用Racket的GUI库，创建一个简单的计算器界面，支持基本的加法、减法、乘法和除法运算。

#lang racket/gui

(define frame (new frame%
                 [label "简单计算器"]
                 [width 300]
                 [height 200]))

(define input-field (new text-field%))

(define output-field (new message%))

(define btn-calculate (new button%
                            [label "计算"]
                            [parent frame]
                            [callback
                             (lambda (button event)
                               (let* ([expression (send input-field get-value)]
                                      [result (eval (read (string-append "(" expression ")")))])
                                 (send output-field set-label (format "结果: ~a" result))))]))

(define btn-clear (new button%
                        [label "清空"]
                        [parent frame]
                        [callback
                         (lambda (button event)
                           (send input-field set-value "")
                           (send output-field set-label "结果: "))]))

(define panel (new horizontal-panel%
                 [items (list input-field btn-calculate btn-clear output-field)]
                 [parent frame]))

(send frame show #t)

免责申明：文章和图片全部来源于公开网络，如有侵权，请通知删除 server@dude6.com