[IT学习]转载python 项目 计算器

这个是从网上搜到的Python小项目之计算器（原文地址：http://www.2cto.com/kf/201402/279637.html）。但该段代码估计是Python 2 写的。

如果你使用的程序是Python 3以上版本，需要自行安装pillow。Windows可以在命令行中使用pip install pillow。

但是在程序中引用时，pillow的名称依然是PIL。具体看下面的例子。

【思考】

1、tkinter 编程要考虑哪些方面？

2、这个程序还有哪些不完善的？例如输入9+-2，看看结果是多少？

3、把电脑里的计算器拿出来看看，对比下，有哪些地方可以完善？

4、grid方式布局有哪些优点，有哪些缺点？

# -*- coding: utf-8 -*-
#author: Cullen
#原来的代码中有这个作者信息，可以以“cullent python”搜搜看，不确定是否同一个人

#import the module
from tkinter import *
import tkinter.font as tkFont
import os
from functools import partial
from PIL import Image, ImageTk

def get_input(entry, argu):
    entry.insert(END, argu)

def backspace(entry):
    input_len = len(entry.get())
    entry.delete(input_len - 1)

def clear(entry):
    entry.delete(0, END)

def calc(entry):
    input = entry.get()
    output = str(eval(input.strip()))
    clear(entry)
    entry.insert(END, output)

def cal():
    root = Tk()
    root.title("Calc")
    root.resizable(0,0)

    entry_font = tkFont.Font(size=12)
    entry = Entry(root, justify="right", font=entry_font)
    entry.grid(row=0, column=0, columnspan=4, sticky=N+W+S+E, padx=5,  pady=5)

    button_font = tkFont.Font(size=10, weight=tkFont.BOLD)
    button_bg = '#D5E0EE'
    button_active_bg = '#E5E35B'

    myButton = partial(Button, root, bg=button_bg, padx=10, pady=3, activebackground = button_active_bg)

    button7 = myButton(text='7', command=lambda : get_input(entry, '7'))
    button7.grid(row=1, column=0, pady=5)

    button8 = myButton(text='8', command=lambda : get_input(entry, '8'))
    button8.grid(row=1, column=1, pady=5)

    button9 = myButton(text='9', command=lambda : get_input(entry, '9'))
    button9.grid(row=1, column=2, pady=5)

    button10 = myButton(text='+', command=lambda : get_input(entry, '+'))
    button10.grid(row=1, column=3, pady=5)

    button4 = myButton(text='4', command=lambda : get_input(entry, '4'))
    button4.grid(row=2, column=0, pady=5)

    button5 = myButton(text='5', command=lambda : get_input(entry, '5'))
    button5.grid(row=2, column=1, pady=5)

    button6 = myButton(text='6', command=lambda : get_input(entry, '6'))
    button6.grid(row=2, column=2, pady=5)

    button11 = myButton(text='-', command=lambda : get_input(entry, '-'))
    button11.grid(row=2, column=3, pady=5)

    button1 = myButton(text='1', command=lambda : get_input(entry, '1'))
    button1.grid(row=3, column=0, pady=5)

    button2 = myButton(text='2', command=lambda : get_input(entry, '2'))
    button2.grid(row=3, column=1, pady=5)

    button3 = myButton(text='3', command=lambda : get_input(entry, '3'))
    button3.grid(row=3, column=2, pady=5)

    button12 = myButton(text='*', command=lambda : get_input(entry, '*'))
    button12.grid(row=3, column=3, pady=5)

    button0 = myButton(text='0', command=lambda : get_input(entry, '0'))
    button0.grid(row=4, column=0, columnspan=2, padx=3, pady=5, sticky=N+S+E+W)

    button13 = myButton(text='.', command=lambda : get_input(entry, '.'))
    button13.grid(row=4, column=2, pady=5)

    button14 = Button(root, text='/', bg=button_bg, padx=10, pady=3,
                      command=lambda : get_input(entry, '/'))
    button14.grid(row=4, column=3, pady=5)

    button15 = Button(root, text='<-', bg=button_bg, padx=10, pady=3,
                      command=lambda : backspace(entry), activebackground = button_active_bg)
    button15.grid(row=5, column=0, pady=5)

    button16 = Button(root, text='C', bg=button_bg, padx=10, pady=3,
                      command=lambda : clear(entry), activebackground = button_active_bg)
    button16.grid(row=5, column=1, pady=5)

    button17 = Button(root, text='=', bg=button_bg, padx=10, pady=3,
                      command=lambda : calc(entry), activebackground = button_active_bg)
    button17.grid(row=5, column=2, columnspan=2, padx=3, pady=5, sticky=N+S+E+W)

    root.mainloop()

if __name__ == '__main__':
    cal()