1

我正在制作一个简单的 Python Tk 计算器，但有一个错误：除非我在输入数字之前按下其中一个按钮，否则计算器将无法工作。之后它会计算输入数字但如果我只是打开它并输入数字它将不起作用

这是我的代码：

from Tkinter import *
import math

def calculate():
    try:
        num1 = float(enter1.get())
        num2 = float(enter2.get())
        result = num1 * num2
        label3.config(text=str(result))
    except ValueError:
        label3.config(text='Enter numeric values!', fg="white")

def calculate2():
    try:
        num1 = float(enter1.get())
        num2 = float(enter2.get())
        result = num1 / num2
        label3.config(text=str(result))
    except ValueError:
        label3.config(text='Enter numeric values!', fg="white")

def calculate3():
    try:
        num1 = float(enter1.get())
        num2 = float(enter2.get())
        result = num1 + num2
        label3.config(text=str(result))
   except ValueError:
        label3.config(text='Enter numeric values!',fg="white")

def calculate4():
    try:
        num1 = float(enter1.get())
        num2 = float(enter2.get())
        result = num1 - num2
        label3.config(text=str(result))
    except ValueError:
        label3.config(text='Enter numeric values!',fg="white")

def calculate5():
    try:
        num1 = float(enter1.get())
        result = num1**2
        label3.config(text=str(result))
    except ValueError:
        label3.config(text='Enter numeric values!',fg="white")

def calculate6():
    try:
        num1 = float(enter1.get())
        result = math.sqrt(num1)
        label3.config(text=str(result))
    except ValueError:
        label3.config(text='Enter numeric values!',fg="white")


root = Tk()
root.configure(background='black')
root.wm_title("Calc")

label1 = Label(root, text='First Number:',bg="black", fg="white")
label1.grid(row=0, column=0,columnspan=2)
enter1 = Entry(root, bg='white')
enter1.grid(row=1, column=0,columnspan=2)

label2 = Label(root, text='Second Number:',bg="black", fg="white")
label2.grid(row=2, column=0,columnspan=2)
enter2 = Entry(root, bg='white')
enter2.grid(row=3, column=0, columnspan=2)

btn1 = Button(root, text='-Multiply-', command=calculate,                                       bg="  black",activebackground="green", fg="white")
btn1.grid(row=4, column=0)
btn2 = Button(root, text='-Divide-', command=calculate2,  bg="black",activebackground="orange", fg="white")
btn2.grid(row=5, column=0)
btn3 = Button(root, text='-Add-', command=calculate3, bg="black",activebackground="purple", fg="white")
btn3.grid(row=5, column=1)
btn4 = Button(root, text='-Subtract-', command=calculate4, bg="black",activebackground="red", fg="white")
btn4.grid(row=4, column=1)
btn5 = Button(root, text='Square (Only First #)', command=calculate5, bg="black",activebackground="cyan", fg="white")
btn5.grid(row=6, column=0, columnspan=2)
btn6 = Button(root, text='Square Root (only First #)', command=calculate6, bg="black",activebackground="yellow", fg="white")
btn6.grid(row=7, column=0, columnspan=2,)
label3 = Label(root, bg="black")
label3.grid(row=8, column=0, columnspan=2)

enter1.focus()
enter1.bind('<Return>', func=lambda e:enter2.focus_set())
root.mainloop()
4

1 回答 1

4

您的代码没有任何问题，唯一的问题是文本颜色最初是黑色的。这就是它在显示错误之前“工作”的原因，因为该选项将选项设置fg为白色，并且在接下来的更改中，它保持已配置的相同文本颜色。

要解决这个问题，只需在创建标签小部件时将fg选项设置为："white"

label3 = Label(root, bg="black", fg="white")
于 2013-05-05T01:33:31.743 回答