40行python代码编写的计算器

from tkinter import *

    reset=True

    def buttonCallBack(event):

        global label

        global reset

        num=event.widget['text']

        if num=='C':

            label['text']="0"

            return

        if num in "=":

            label['text']=str(eval(label['text']))

            reset=True

            return

        s=label['text']

        if s=='0' or reset==True:

            s=""

            reset=False

        label['text']=s+num

#主窗口  
root=Tk()  
root.wm_title("计算器")  
#显示栏1  
label=Label(root,text="0",background="white",anchor="e")  
label['width']=35  
label['height']=2  
label.grid(row=1,columnspan=4,sticky=W)  
#按钮  
showText="789/456*123-0.C+"  
for i in range(4):  
    for j in range(4):  
        b=Button(root,text=showText[i*4+j],width=7)  
        b.grid(row=i+2,column=j)  
        b.bind("<Button-1>",buttonCallBack)  
showText="()"  
for i in range(2):  
    b=Button(root,text=showText[i],width=7)  
    b.grid(row=6,column=2+i)  
    b.bind("<Button-1>",buttonCallBack)  
b=Button(root,text="=")  
b.grid(row=6,columnspan=2,sticky="we")  
b.bind("<Button-1>",buttonCallBack)  
root.mainloop()  </pre>