python 计算器

--coding:utf-8--

from Tkinter import *

创建横条型框架

def frame(root, side):
w = Frame(root)
w.pack(side = side, expand = YES, fill = BOTH)
return w

创建按钮

def button(root, side, text, command = None):
w = Button(root, text = text, command = command)
w.pack(side = side, expand = YES, fill = BOTH)
return w

继承了Frame类，初始化程序界面的布局

class Calculator(Frame):
def init(self):

    Frame.__init__(self)

    self.pack(expand = YES, fill = BOTH)
    self.master.title('Simple Calculater')

    display = StringVar()
    #添加输入框
    Entry(self, relief = SUNKEN,
          textvariable = display).pack(side = TOP, expand = YES,
                                       fill = BOTH)
    #添加横条型框架以及里面的按钮
    for key in('123', '456', '789', '-0.'):
        keyF = frame(self, TOP)
        for char in key:
            button(keyF, LEFT, char, lambda w = display, c = char:w.set(w.get() + c))
    #添加操作符按钮
    opsF = frame(self, TOP)
    for char in '+-*/=':
        if char == '=':
            btn = button(opsF, LEFT, char)
            btn.bind('<ButtonRelease - 1>', lambda e, s = self, w = display:s.calc(w), '+')

        else:
            btn = button(opsF, LEFT, char, lambda w = display, s = '%s' %char:w.set(w.get() + s))
    #添加清除按钮
    clearF = frame(self, BOTTOM)
    button(clearF, LEFT, 'clear', lambda w = display:w.set(''))

#调用eval函数计算表达式的值
def calc(self, display):
    try:
        display.set(eval(display.get()))
    except:
        display.set("ERROR")

程序的入口

if name == 'main':
print('ok')
Calculator().mainloop()