python entry 获取_python3 tkinter 获取Entry值报错

#!/usr/bin/env python

# encoding: utf-8

from tkinter import *

top = Tk()

top.title('计算器')

top.grid_size()

label0 = Label(top, text='计算器', font='仿宋 24 bold', width=20, height=2)

label0.grid(row=0, column=1, columnspan=3, rowspan=2)

label1 = Label(top, text='输入参数一：', font='楷体 13', width=16, height=1)

label1.grid(row=2, column=0)

label2 = Label(top, text='输入参数二：', font='楷体 13', width=16, height=1)

label2.grid(row=3, column=0)

input1 = Entry(top, width=20)

data1 = int(input1.get())

input1.grid(row=2, column=1)

input2 = Entry(top, width=20)

data2 = int(input2.get())

input2.grid(row=3, column=1)

button1 = Button(top, text='滚加', width=20, height=1)

button1.grid(row=6, column=0)

jieguo = Text(top, width=40, height=6)

jieguo.grid(row=2, column=2, rowspan=4, columnspan=2)

button6 = Button(top, text='退出', command=top.quit(), width=110)

button6.grid(row=8, column=0, columnspan=5)

mainloop()

做的一个小计算器，具体计算过程还没写，刚写了一个可视界面，运行时报错，问问各位大神，(=@__@=)哪里错了

data1 = int(input1.get())

ValueError: invalid literal for int() with base 10: ''