[原]随想录（python编写的计算器）

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python除了用来开发server、web之外，一般还可以用来开发客户端，特别是用来做一些demo原型还是比较合适的。这里找了一份python编写的计算器，供大家参考一下。代码出处在 这 。

import Tkinter as tk calc = tk.Tk() calc.title("CrappyCalc") buttons = [ '7', '8', '9', '*', 'C', '4', '5', '6', '/', 'Neg', '1', '2', '3', '-', '$', '0', '.', '=', '+', '@' ] # set up GUI row = 1 col = 0 for i in buttons: button_style = 'raised' action = lambda x = i: click_event(x) tk.Button(calc, text = i, width = 7, height = 7, relief = button_style, command = action) \ .grid(row = row, column = col, sticky = 'nesw', ) col += 1 if col > 4: col = 0 row += 1 display = tk.Entry(calc, width = 40, bg = "white") display.grid(row = 0, column = 0, columnspan = 5) def click_event(key): # = -> calculate results if key == '=': # safeguard against integer division if '/' in display.get() and '.' not in display.get(): display.insert(tk.END, ".0") # attempt to evaluate results try: result = eval(display.get()) display.insert(tk.END, " = " + str(result)) except: display.insert(tk.END, " Error, use only valid chars") # C -> clear display elif key == 'C': display.delete(0, tk.END) # $ -> clear display elif key == '$': display.delete(0, tk.END) display.insert(tk.END, "$$$$C.$R.$E.$A.$M.$$$$") # @ -> clear display elif key == '@': display.delete(0, tk.END) display.insert(tk.END, "wwwwwwwwwwwwwwwwebsite") # neg -> negate term elif key == 'neg': if '=' in display.get(): display.delete(0, tk.END) try: if display.get()[0] == '-': display.delete(0) else: display.insert(0, '-') except IndexError: pass # clear display and start new input else: if '=' in display.get(): display.delete(0, tk.END) display.insert(tk.END, key) # RUNTIME calc.mainloop()

大家可以在此基础上做一些改写，比如如果没有eval函数，怎么用状态机来进行设计呢？