class Counter:  #引入tkinter  import tkinter as tk  #引入消息彈窗模塊  import tkinter.messagebox as mbox   #初始化Counter  def __init__(self):   #生成一個窗口對象   self.window = self.tk.Tk()   #命名窗口對象的顯示title   self.window.title('計算器')   #設(shè)置窗口的大小   self.window.minsize(240, 325)   self.window.maxsize(240, 325)   #是否清空顯示框判定參數(shù)   self.is_init_lable = False   #設(shè)置菜單   self.set_menu()   #設(shè)置顯示框   self.lable_show = self.tk.Label(text='', anchor='se', font=('黑體', 30), fg='black')   self.lable_show.place(x=0, y=0, width=240, height=80)   #設(shè)置按鈕組件   self.set_buttons()   #將窗口放入主消息隊列   self.window.mainloop()   #設(shè)置菜單  def set_menu(self):   #創(chuàng)建總菜單   menubar = self.tk.Menu(self.window)   #創(chuàng)建一個下拉菜單，并且加入文件菜單   filemenu = self.tk.Menu(menubar, tearoff=0)   #創(chuàng)建下來菜單的選項   filemenu.add_command(label="退出計算器", command=self.window.quit)   #print author的函數(shù)   def show_author():    self.mbox.showinfo(message='Wiz333@XDL 2017')   filemenu.add_command(label="作者", command=show_author)   #將文件菜單作為下拉菜單添加到總菜單中，并且將命名為操作   menubar.add_cascade(label="操作", menu=filemenu)   #顯示總菜單   self.window.config(menu=menubar)   #設(shè)置按鈕組件  def set_buttons(self):   #7   btn7 = self.tk.Button(text='7', bd=2, font='黑體')   btn7.place(x=0, y=90, width=60, height=40)   #8   btn8 = self.tk.Button(text='8', bd=2, font='黑體')   btn8.place(x=60, y=90, width=60, height=40)   #9   btn9 = self.tk.Button(text='9', bd=2, font='黑體')   btn9.place(x=120, y=90, width=60, height=40)   #+   btn_jia = self.tk.Button(text='+', bd=2, font='黑體')   btn_jia.place(x=180, y=90, width=60, height=40)   #4   btn4 = self.tk.Button(text='4', bd=2, font='黑體')   btn4.place(x=0, y=130, width=60, height=40)   #5   btn5 = self.tk.Button(text='5', bd=2, font='黑體')   btn5.place(x=60, y=130, width=60, height=40)   #6   btn6 = self.tk.Button(text='6', bd=2, font='黑體')   btn6.place(x=120, y=130, width=60, height=40)   #-   btn_jian = self.tk.Button(text='-', bd=2, font='黑體')   btn_jian.place(x=180, y=130, width=60, height=40)   #1   btn1 = self.tk.Button(text='1', bd=2, font='黑體')   btn1.place(x=0, y=170, width=60, height=40)   #2   btn2 = self.tk.Button(text='2', bd=2, font='黑體')   btn2.place(x=60, y=170, width=60, height=40)   #3   btn3 = self.tk.Button(text='3', bd=2, font='黑體')   btn3.place(x=120, y=170, width=60, height=40)   #*   btn_cheng = self.tk.Button(text='*', bd=2, font='黑體')   btn_cheng.place(x=180, y=170, width=60, height=40)   #0   btn0 = self.tk.Button(text='0', bd=2, font='黑體')   btn0.place(x=0, y=210, width=120, height=40)   #.   btn_point = self.tk.Button(text='.', bd=2, font='黑體')   btn_point.place(x=120, y=210, width=60, height=40)   #/   btn_chu = self.tk.Button(text='/', bd=2, font='黑體')   btn_chu.place(x=180, y=210, width=60, height=40)   #取消   btn_cancel = self.tk.Button(text='C', bd=2, font='黑體')   btn_cancel.place(x=0, y=250, width=60, height=40)   #確定   btn_ok = self.tk.Button(text='=', bd=2, font='黑體')   btn_ok.place(x=60, y=250, width=180, height=40)   #綁定Button的點擊事件   btn7.bind_class('Button', '<Button-1>', self.click_button)   #綁定Button的點擊事件  def click_button(self,e):   #判斷是否是新的運算,如果是則清空顯示框   if self.is_init_lable:    self.lable_show['text'] = ''    self.is_init_lable = False   #label_show顯示的累加   font = e.widget['text']   self.lable_show['text'] += font   #異常捕獲   try:    #判定運算符號重復的時候,使用最后輸入的符號    if self.lable_show['text'][-1] in ['+','-','*','/'] and self.lable_show['text'][-2] in ['+','-','*','/']:     header = self.lable_show['text'][:-2]     footer = self.lable_show['text'][-1]     self.lable_show['text'] = header+footer   except:    pass    #普通計算   if e.widget['text'] == '=':    try:     res = eval(self.lable_show['text'][:-1])     #print(res)     #小數(shù)點取到9位     self.lable_show['text'] = str(round(float(res), 5))     self.isinit = True    except ZeroDivisionError:     #除法時，除數(shù)不能為0     self.mbox.showerror(message='除法計算時！除數(shù)不能為0！')    except:     self.mbox.showerror(message='算式有誤')   #取消當前輸入的字符   if e.widget['text'] == 'C':    cancel_res = self.lable_show['text'][:-2]    self.lable_show['text'] = cancel_res   #實例化計算器對象 wiz = Counter()