[Python知识库]使用python制作一个简单的计算器

这个迷你demo主要用到的是Tkinter模块。

准备工作:pip3 install tkinter

from tkinter import Tk, END, Entry, N, E, S, W
from tkinter import font
from tkinter import Label
from functools import partial

# 使用tkmacosx模块中的Button,是因为tkinter无法在mac上设置按钮颜色
from tkmacosx import Button

def get_input(entry, argu):
    # 将输入的值或符号添加到文本框末尾
    entry.insert(END, argu)

def backspace(entry):
    # 点击'CE'时,删除最后一个字符
    # delete通过传入参数来指定删除文本,(input_len-1)为起始，默认last为终止
    input_len = len(entry.get())
    entry.delete(input_len-1)

def clear(entry):
    # 删除从0到END的内容,即全部清除。
    entry.delete(0, END)

def calc(entry):
    input_info = entry.get()
    try:
        # 当点击'='号时，通过eval去计算表达式的值
        output = str(eval(input_info.strip()))
    except ZeroDivisionError:
        popupmsg()
        output = ""
    clear(entry)
    entry.insert(END, output)

def popupmsg():
    """
    发生除以0时,弹出异常
    :return:
    """
    popup = Tk()
    popup.resizable(0, 0)
    popup.geometry("120x100")
    popup.title("Alert")

    lable = Label(popup, text="Connot divide by 0 ! \n Enter vaild values")
    lable.pack(side="top", fill="x", pady=10)

    B1 = Button(popup, text="OKay", bg="#DDDDDD", command=popup.destroy)
    B1.pack()

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

    entry_font = font.Font(size=15)

    # Entry：创建单行文本框，用来显示要运算的公式和输出的结果
    entry = Entry(root, justify="right", font=entry_font)
    # 设置Entry的属性
    entry.grid(row=0, column=0, columnspan=4,
               sticky=N + W + S + E, padx=5, pady=5)

    # 设置颜色
    cal_button_bg = 'black'
    num_button_bg = 'green'
    other_button_bg = 'orange'
    text_fg = 'red'
    button_active_bg = 'orange'

    # 对数字按钮和运算符按钮中相同的属性提前进行封装
    num_button = partial(Button, root, fg=text_fg, bg=num_button_bg, padx=10,
                         pady=3, activebackground=button_active_bg)
    cal_button = partial(Button, root, fg=text_fg, bg=cal_button_bg, padx=10,
                         pady=3, activebackground=button_active_bg)

    # 第1行为 'CE','C','/'
    button16 = Button(root, text='CE', bg=other_button_bg, padx=10, pady=3,
                      command=lambda: backspace(entry), activebackground=button_active_bg)
    button16.grid(row=1, column=0, columnspan=2,
                  padx=3, pady=5, sticky=N + W + S + E)

    button17 = Button(root, text='C', bg=other_button_bg, padx=10, pady=3,
                      command=lambda: clear(entry), activebackground=button_active_bg)
    button17.grid(row=1, column=2, pady=5)

    button18 = Button(text='/', fg=text_fg, bg=cal_button_bg, padx=10, pady=3,
                      command=lambda: get_input(entry, '/'))
    button18.grid(row=1, column=3, pady=5)

    # 第二行为数字7-9和'*'
    button7 = num_button(text='7', command=lambda: get_input(entry, '7'))
    button7.grid(row=2, column=0, pady=5)

    button8 = num_button(text='8', command=lambda: get_input(entry, '8'))
    button8.grid(row=2, column=1, pady=5)

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

    button10 = cal_button(text='*', command=lambda: get_input(entry, '*'))
    button10.grid(row=2, column=3, pady=5)

    # 第三行为数字4-6和'-'
    button4 = num_button(text='4', command=lambda: get_input(entry, '4'))
    button4.grid(row=3, column=0, pady=5)

    button5 = num_button(text='5', command=lambda: get_input(entry, '5'))
    button5.grid(row=3, column=1, pady=5)

    button6 = num_button(text='6', command=lambda: get_input(entry, '6'))
    button6.grid(row=3, column=2, pady=5)

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

    # 第三行为数字1-3和'+'
    button1 = num_button(text='1', command=lambda: get_input(entry, '1'))
    button1.grid(row=4, column=0, pady=5)

    button2 = num_button(text='2', command=lambda: get_input(entry, '2'))
    button2.grid(row=4, column=1, pady=5)

    button3 = num_button(text='3', command=lambda: get_input(entry, '3'))
    button3.grid(row=4, column=2, pady=5)

    button12 = cal_button(text='+', command=lambda: get_input(entry, '+'))
    button12.grid(row=4, column=3, pady=5)

    # 第五行为'.',0,幂,'='
    button13 = num_button(text='.', command=lambda: get_input(entry, '.'))
    button13.grid(row=5, column=0, pady=5)

    button0 = num_button(text='0', command=lambda: get_input(entry, '0'))
    button0.grid(row=5, column=1, pady=5)

    button14 = Button(root, text='^', fg=text_fg, bg=cal_button_bg, padx=10, pady=3,
                          command=lambda: get_input(entry, '**'))
    button14.grid(row=5, column=2, pady=5)

    button15 = Button(root, text='=', fg=text_fg, bg=cal_button_bg, padx=10, pady=3,
                          command=lambda: calc(entry), activebackground=button_active_bg)
    button15.grid(row=5, column=3, pady=5)

    root.mainloop()

if __name__ == '__main__':
    cal()

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