(9)用tkinter模块写简易计算器

利用python中的tkinter模块，主要模仿win7系统自带的标准型计算器，实现基本运算功能，运行程序后如下图所示：

未实现功能（待完善）：

1.小数点可以按很多次问题没有解决
2.若有浮点类型数计算精度问题未解决
3.一些未知小BUG，需调试完善的地方还很多

以下是具体代码，面向过程开发，程序很小面向对象的写法也很简单，这里不再给出（代码在linux系统下的pycharm中书写）

import tkinter
import tkinter.messagebox
import math
root = tkinter.Tk()
root.title('银河超级计算器')
root.minsize(350,400)
# 设置菜单
# 设置总菜单
allmenu = tkinter.Menu()

# 添加子菜单
look = tkinter.Menu(tearoff = 0)  # 查看
edit = tkinter.Menu(tearoff = 0)  # 编辑
help = tkinter.Menu(tearoff = 0)  # 帮助
auther = tkinter.Menu(tearoff = 0)# 作者

'''
向子菜单中添加选项卡未作！！！！
'''
# 将子菜单加入总菜单
allmenu.add_cascade(menu = look, label = '查看')
allmenu.add_cascade(menu = edit, label = '编辑')
allmenu.add_cascade(menu = help, label = '帮助')
allmenu.add_cascade(menu = auther, label = '作者')

# 摆放总菜单
root.config(menu = allmenu)

# 文本输入框
v = tkinter.StringVar()
v.set('0')
label = tkinter.Label(textvariable = v, bg = 'white',font =('黑体',20),
                       bd = 5, anchor = 'se')
label.place(x = 30, y = 15, width = 290, height = 60)

# 声明一个用于保存运算过程的容器
operationlist = []

# 声明一个是否按下运算符号的变量
ispresssign = False

# 声明一个是否按下等于键的变量
ispressflag = False

# 声明一个是否允许按下'.'键的变量
isdot = True

# 按下数字的函数
def pressnum(num):
    # 全局化变量
    global ispresssign
    global operationlist
    global ispressflag
    global isdot
    # 判断是否按下等于键
    if ispressflag == True:
        # 将数字归0
        v.set('0')
        # 重置判断符
        ispressflag = False
    # 判断是否按下运算的符号
    if ispresssign == True:
        # 将数字归0
        v.set('0')
        # 重置运算符
        ispresssign = False

    # 获取面板原有数字
    oldnum = v.get()
    # 判断原数字是否为0
    if oldnum == '0':   # 直接显示按下的数字
        if num == '.' and isdot == True:
            v.set('0' + '.')
            isdot = False
        else:
            v.set(num)

        # 判断是否按下1/x键
        if num == '1/x':
            if oldnum == '0':
                v.set('除数不能为0')
            else:
                result = 1 / float(oldnum)
                v.set(result)

        # 判断是否按下撤销键（ ← 键）
        if num == '←':
            operationlist.clear()
            v.set('0')
    else:  # 将原数字与当前数字拼和
        # 判断是否按下正负号
        if num == '±':
            if oldnum.startswith('-'):
                v.set(oldnum[1:])
            else:
                v.set('-' + oldnum)

        else:
            v.set(oldnum + num)

        # 判断是否按下撤销键（ ← 键）
        if num == '←':
            if len(oldnum) == 1:
                v.set('0')
            else:

             v.set(oldnum[:-1])

        # 判断是否按下根号键
        if num == '√':
            result = math.sqrt(float(oldnum))
            v.set(result)

    # 判断是否按下了清空键 （C 或者CE键）
    if num == 'C' or num == 'CE':
        operationlist.clear()
        v.set('0')

# 按下运算符号的函数
def presssign(sign):
    # 全局化变量
    global ispresssign
    global operationlist
    global isdot

    if ispresssign == True:
        operationlist[-1] = sign
    else:
         # 获取页面中的原有数字
        oldnum = v.get()
        # 将页面原有数字保存到列表中
        operationlist.append(oldnum)
        # 保存运算符号
        operationlist.append(sign)
        # 设置按下运算符的标志
        ispresssign = True
    isdot = True

# 按下等号的函数
def pressequal():
    # 全局化
    global operationlist
    global ispressflag
    # 获取界面中的数字
    oldnum = v.get()
    if oldnum == '0' and '/' in operationlist:
        operationlist.clear()
        v.set('除数不能为0')
        ispressflag = True
    else:
    # 将列表中的运算组合到一起
        operationlist.append(oldnum)
    #print(operationlist)

    # 将列表中的步骤组合成字符串使用eval运算
        result = eval(''.join(operationlist))

    # 显示结果
        v.set(result)

    # 清空运算列表
        operationlist.clear()
        ispressflag = True

# 按钮
btnchexiao = tkinter.Button(text = '←', command = lambda : pressnum('←'))
btnchexiao.place(x = 30, y = 90, width = 50, height = 40)

btnCE = tkinter.Button(text = 'CE', command = lambda : pressnum('C'))
btnCE.place(x = 90, y = 90, width = 50, height = 40 )

btnC = tkinter.Button(text = 'C', command = lambda :pressnum('CE'))
btnC.place(x = 150, y = 90, width = 50, height = 40 )

btnflag = tkinter.Button(text = '±', command = lambda : pressnum('±'))
btnflag.place(x = 210, y = 90, width = 50, height = 40 )

btngen = tkinter.Button(text = '√', command = lambda : pressnum('√'))
btngen.place(x = 270, y = 90, width = 50, height = 40 )

btn7 = tkinter.Button(text = '7', command = lambda : pressnum('7'))
btn7.place(x = 30, y = 140, width = 50, height = 40 )

btn8 = tkinter.Button(text = '8', command = lambda : pressnum('8'))
btn8.place(x = 90, y = 140, width = 50, height = 40 )

btn9 = tkinter.Button(text = '9', command = lambda : pressnum('9'))
btn9.place(x = 150, y = 140, width = 50, height = 40 )

btnchu = tkinter.Button(text = '/',command = lambda : presssign('/'))
btnchu.place(x = 210, y = 140, width = 50, height = 40 )

btnyu = tkinter.Button(text = '%', command = lambda : presssign('%'))
btnyu.place(x = 270, y = 140, width = 50, height = 40 )

btn4 = tkinter.Button(text = '4', command = lambda : pressnum('4'))
btn4.place(x = 30, y = 190, width = 50, height = 40 )

btn5 = tkinter.Button(text = '5', command = lambda : pressnum('5'))
btn5.place(x = 90, y = 190, width = 50, height = 40 )

btn6 = tkinter.Button(text = '6', command = lambda : pressnum('6'))
btn6.place(x = 150, y = 190, width = 50, height = 40 )

btncheng = tkinter.Button(text = '*', command = lambda : presssign('*'))
btncheng.place(x = 210, y = 190, width = 50, height = 40 )

btndao = tkinter.Button(text = '1/x', command = lambda : pressnum('1/x'))
btndao.place(x = 270, y = 190, width = 50, height = 40 )

btn1 = tkinter.Button(text = '1', command = lambda : pressnum('1'))
btn1.place(x = 30, y = 240, width = 50, height = 40 )

btn2 = tkinter.Button(text = '2', command = lambda : pressnum('2'))
btn2.place(x = 90, y = 240, width = 50, height = 40 )

btn3 = tkinter.Button(text = '3', command = lambda : pressnum('3'))
btn3.place(x = 150, y = 240, width = 50, height = 40 )

btnjian = tkinter.Button(text = '-', command = lambda : presssign('-'))
btnjian.place(x = 210, y = 240, width = 50, height = 40 )

btndeng = tkinter.Button(text = '=', command = pressequal)
btndeng.place(x = 270, y = 240, width = 50, height = 90 )

btnling = tkinter.Button(text = '0', command = lambda : pressnum('0'))
btnling.place(x = 30, y = 290, width = 110, height = 40 )

btndot = tkinter.Button(text = '.', command = lambda : pressnum('.'))
btndot.place(x = 150, y = 290, width = 50, height = 40 )

btnjia = tkinter.Button(text = '+', command = lambda : presssign('+'))
btnjia.place(x = 210, y = 290, width = 50, height = 40 )

# 绑定查看源代码事件
def look():
    tkinter.messagebox.showinfo(title = '嘿嘿嘿～～',message = '想得美，滚蛋滚蛋！！')

btnlook = tkinter.Button(text = '点击查看源代码', bg = 'black', fg = 'white', bd = 5, command = look)
btnlook.place(x = 90, y = 350, width = 170, height = 30)

root.mainloop()