python tkinter如何清空窗体 python tkinter 删除控件

# _*_ coding: utf-8 _*_ # @Time 2022/10/18 19:49 # @file dwj_计算器1.0.py # @software PyCharm # Author:Destiney

import tkinter as tk # tkinter是用于构建图形用户界面 (GUI) 的控件集

# 定义两个字体变量
font_20 = ('宋体', 20)
font_16 = ('华文楷体', 16)
# 布局
root = tk.Tk()  # 实例化一个窗体对象
root.title('counting machine')  # 设置窗口标题
root.geometry('300x280+100+100')
"""将root窗口的宽和高设置成300x250 注意x号而非*；
加号后的两个数字，就是调整窗口在电脑屏幕上的位置，
第1个加号是距离屏幕左边的宽，第2个加号是距离屏幕顶部的高。
注意加号后面可以跟负数，这是一种隐藏窗口的方式：
"""
# window_x = root.winfo_screenwidth()  # 获取电脑屏幕窗口宽度
# window_y = root.winfo_screenheight()  # 获取电脑屏幕窗口高度
# print(window_x)
# print(window_y)
# 以上四行目的是为了知道我的窗口尺寸以便设置计算器窗口的位置 得知之后便注释掉了
root.resizable(width=True, height=True)  # 将窗口高宽设置为可更改
root.maxsize(1493, 933) # 设置计算器窗口可调整的最大最小尺寸，
root.minsize(100, 150)
root.attributes('-alpha', 0.9)  # 设置透明度为0.9,参数为0~1
root['background'] = '#f0f8ff'  # 设置背景颜色为古董白

result_num = tk.StringVar()  # 设置一个字符串变量
result_num.set('')  # 将初始值设置为0

# lable 用于显示不可编辑的文本和图标
tk.Label(root,    
         textvariable=result_num,
         font=font_20, height=2, width=20, justify=tk.LEFT,
         anchor=tk.SE).grid(row=1, column=1, columnspan=4)

#  textvariable 指定一个变量，GUI组件负责展示该变量值转换得到的字符串，
#  font 指定字体颜色  justify 针对多行文字对齐，对齐方式有left，center，right
# anchor对齐方式s底对齐e右对齐
# grid布局：行列
# 设置第一行的按钮 Button（）函数
button_clear = tk.Button(root, text='C', bg='pink', width=5, # 按钮组件
                         font=font_16, relief=tk.FLAT)
# button 用来执行用户的单击操作
# relief 指定组件的3D效果，FLAT为扁平
button_back = tk.Button(root, text='←',
                        bg='pink', width=5, font=font_16, relief=tk.FLAT)
button_division = tk.Button(root, text='/', bg='pink', width=5,
                            font=font_16, relief=tk.FLAT)
button_multiplication = tk.Button(root, text='x',
                                  bg='pink', width=5, font=font_16, relief=tk.FLAT)
button_clear.grid(row=2, column=1, padx=4, pady=2)
# padx 指定组件内部水平方向两边的空白 pady：指定组件内部垂直方向两边的空白
# row表示单元格的行号，column 单元格的列号
button_back.grid(row=2, column=2, padx=4, pady=2)
button_division.grid(row=2, column=3, padx=4, pady=2)
button_multiplication.grid(row=2, column=4, padx=4, pady=2)

# 设置第二行的按钮
button_seven = tk.Button(root, text='7', bg='#b1b2b2', width=5,
                         font=font_16, relief=tk.FLAT)
button_eight = tk.Button(root, text='8',
                         bg='#b1b2b2', width=5, font=font_16, relief=tk.FLAT)
button_nine = tk.Button(root, text='9', bg='#b1b2b2', width=5,
                        font=font_16, relief=tk.FLAT)
button_subtraction = tk.Button(root, text='-',
                               bg='pink', width=5, font=font_16, relief=tk.FLAT)
button_seven.grid(row=3, column=1, padx=4, pady=2)
button_eight.grid(row=3, column=2, padx=4, pady=2)
button_nine.grid(row=3, column=3, padx=4, pady=2)
button_subtraction.grid(row=3, column=4, padx=4, pady=2)

# 设置第3行的按钮
button_four = tk.Button(root, text='4', bg='#b1b2b2', width=5,
                        font=font_16, relief=tk.FLAT)
button_five = tk.Button(root, text='5',
                        bg='#b1b2b2', width=5, font=font_16, relief=tk.FLAT)
button_six = tk.Button(root, text='6', bg='#b1b2b2', width=5,
                       font=font_16, relief=tk.FLAT)
button_addition = tk.Button(root, text='+',
                            bg='pink', width=5, font=font_16, relief=tk.FLAT)
button_four.grid(row=4, column=1, padx=4, pady=2)
button_five.grid(row=4, column=2, padx=4, pady=2)
button_six.grid(row=4, column=3, padx=4, pady=2)
button_addition.grid(row=4, column=4, padx=4, pady=2)

# 设置第4行的按钮
button_one = tk.Button(root, text='1', bg='#b1b2b2', width=5,
                       font=font_16, relief=tk.FLAT)
button_two = tk.Button(root, text='2',
                       bg='#b1b2b2', width=5, font=font_16, relief=tk.FLAT)
button_three = tk.Button(root, text='3', bg='#b1b2b2', width=5,
                         font=font_16, relief=tk.FLAT)
button_equal = tk.Button(root, text='=',
                         bg='pink', width=5, height=3, font=font_16, relief=tk.FLAT)
button_one.grid(row=5, column=1, padx=4, pady=2)
button_two.grid(row=5, column=2, padx=4, pady=2)
button_three.grid(row=5, column=3, padx=4, pady=2)
button_equal.grid(row=5, column=4, padx=4, pady=2, rowspan=2)
# grid布局 rowspan：组件跨多少列表格框，默认1个组件占用1行1列
# 设置第5行的按钮
button_zero = tk.Button(root, text='0', bg='#b1b2b2', width=12,
                        font=font_16, relief=tk.FLAT)
button_dot = tk.Button(root, text='.',
                       bg='#b1b2b2', width=5, font=font_16, relief=tk.FLAT)
# button_equal2 = tk.Button(root, text='=', bg='#b1b2b2',width=5,
#                          font=font_16, relief=tk.FLAT)
button_zero.grid(row=6, column=1, padx=4, pady=2, columnspan=2)
# grid布局 columnspan ：组件跨多少行表格框，默认1个组件占用1行1列
button_dot.grid(row=6, column=2 and 3, padx=4, pady=2)


# button_equal2.grid(row=6,column=4,padx=4,pady=2)


# 运算逻辑
def click_button(x): # 连接字符串
    print('x:\t')
    result_num.set((result_num.get() + x))


def calculation():  # 字符串转为算术运算
    opt_str = result_num.get()
    result = eval（opt_str)
    result_num.set(str(result))
    
# 起初result_num设置的是字符串因而在screen上显示的时候需要str（）函数


def back():  # 删除
    a = result_num.get()
    a = a [:-1]  # 删除结尾
    result_num.set(a)

def clear(): # 清空
    a = result_num.get()
    a = ''  # 删除结尾
    result_num.set(a)

button_one.config(command=lambda: click_button('1'))
button_two.config(command=lambda: click_button('2'))
button_three.config(command=lambda: click_button('3'))
button_four.config(command=lambda: click_button('4'))
button_five.config(command=lambda: click_button('5'))
button_six.config(command=lambda: click_button('6'))
button_seven.config(command=lambda: click_button('7'))
button_eight.config(command=lambda: click_button('8'))
button_nine.config(command=lambda: click_button('9'))
button_zero.config(command=lambda: click_button('0'))
button_dot.config(command=lambda: click_button('.'))
button_division.config(command=lambda: click_button('/'))
button_multiplication.config(command=lambda: click_button('*')) #因为后面eval（）的关系而用*而不是x
# eval（）函数 将字符串str当成有效的表达式来求值并返回计算结果。
button_addition.config(command=lambda: click_button('+'))
button_subtraction.config(command=lambda: click_button('-'))
button_equal.config(command=lambda: click_button('='))

# 计算
button_equal.config(command=calculation)  # 使用command=lambda: 的形式传参
button_back.config(command=back) # 使用command=lambda: 的形式传参
# config用来配置tkinter中控件和字体的样式，比如颜色、大小等。
button_clear.config(command=clear) # 使用command=lambda: 的形式传参
root.mainloop()   # 进入事件循环