if/else语句上的随机tkinter窗口打开

Question

我想知道我的if-else语句是错的，还是tkinter问题。我希望这样，如果在任何或所有框中都留下0，它就会显示一条错误消息。但在关闭错误消息后，它会打开一个随机的空白窗口。这是我的密码。特定区域是函数valueget((中的if-else语句

import tkinter as tk
def mainwindow():    
mainwindow = tk.Tk()
mainwindow.title('Enter values')
mainwindow.geometry('160x110')
mainwindow.config(bg='#aaf0d1')
tk.Label(mainwindow, text = 'Enter a', font = ('verdana'),  bg='#aaf0d1').grid(row=0)
tk.Label(mainwindow, text = 'Enter b', font = ('verdana'),  bg='#aaf0d1').grid(row=1)
tk.Label(mainwindow, text = 'Enter c', font = ('verdana'),  bg='#aaf0d1').grid(row=2)
getA = tk.IntVar()
aBox = tk.Entry(mainwindow, textvariable = getA, width=3,  bg='#aaf0d1')
aBox.grid(row=0, column=1)
aBox.config(highlightbackground='#aaf0d1')                
getB = tk.IntVar()
bBox = tk.Entry(mainwindow, textvariable = getB, width=3,  bg='#aaf0d1')
bBox.grid(row=1, column=1)
bBox.config(highlightbackground='#aaf0d1')
getC = tk.IntVar()
cBox = tk.Entry(mainwindow, textvariable = getC, width=3,  bg='#aaf0d1')
cBox.grid(row=2, column=1)
cBox.config(highlightbackground='#aaf0d1')
button = tk.Button(mainwindow, text='Obtain roots', command = lambda: valueget(), font = ('verdana'), highlightbackground='#aaf0d1')
button.grid(row=4)
button.config(bg='#aaf0d1')
def valueget():    
readA = getA.get()
readB = getB.get()
readC = getC.get()

intA = int(readA)
intB = int(readB)
intC = int(readC)
negroot = (readB**2)-(4*readA*readC)
quadformulaplus = (-readB + (pow(negroot,0.5)))/(2*readA) #quad forumla
quadformulaminus = (-readB - (pow(negroot,0.5)))/(2*readA) #quad forumla

messagewindow = tk.Tk()
messagewindow.geometry('290x50')
messagewindow.title('Roots of the equation')
messagewindow.config(bg='#aaf0d1')

if readA == 0 or readB==0 or readC==0 or (readA==0 and readB==0 and readC==0):
errorwindow = tk.messagebox.showerror(message='none').pack()
else:                  
label = tk.Label(messagewindow, text = f'The roots are {quadformulaplus:.1f} and {quadformulaminus:.1f}', bg='#aaf0d1', font = ('verdana'))
label.grid(row=1)
closebutton = tk.Button(messagewindow, text='Close', command = lambda: messagewindow.destroy(), font = ('verdana'), highlightbackground='#aaf0d1')
closebutton.grid(row=2)
closebutton.config(bg='#aaf0d1')
messagewindow.mainloop()
# print(f'the roots are {quadformulaplus:.1f} and {quadformulaminus:.1f}')
mainwindow.mainloop()

def startup():
startpage = tk.Tk()
startpage.title('Solver')
photo = tk.PhotoImage(file = r"/Users/isa/Desktop/DiffEqns/cover.png")  #image load
coverbutton = tk.Button(startpage, image = photo, command = lambda: [startpage.destroy(), mainwindow()])
coverbutton.pack()
coverbutton.configure(highlightbackground='#aaf0d1')
startpage.mainloop()
startup()

Answer 1

以下是我要做的一个基本想法：

import tkinter as tk
from tkinter import messagebox
def mainwindow(root):
# Creates a toplevel window
mainwindow = tk.Toplevel()
mainwindow.protocol("WM_DELETE_WINDOW", root.destroy) # This overrides the "X" being clicked to also destroy the root window.
root.withdraw() # "Hides" the root window, leaving it (and mainloop) running in the background.
mainwindow.title('Enter values')
mainwindow.geometry('160x110')
mainwindow.config(bg='#aaf0d1')
# Since all three of the labels/entries are the same
# we can save space by generating them in a loop
entry_items = ('Enter a', 'Enter b', 'Enter c')
values = []
for x, item in enumerate(entry_items): # Using enumerate and x to assign rows
tk.Label(mainwindow, text = item,
font = ('verdana'),  bg='#aaf0d1').grid(row=x) # Row assigned to x.
values.append(tk.StringVar()) # Appended StringVar to list.
tk.Entry(mainwindow,
textvariable = values[-1], # Uses the last value appended to the values list.
highlightbackground='#aaf0d1',
width=3,
bg='#aaf0d1').grid(row=x, column=1) # Row assigned to x.     
tk.Button(mainwindow,
text='Obtain roots',
command = lambda vals = values: valueget(vals), # Here the button command is assigned with the values list
font = ('verdana'), bg='#aaf0d1',
highlightbackground='#aaf0d1').grid(row=3) # we know there are 3 items before this.
mainwindow.lift() # This is a method of bringing a window to the front
def valueget(vals):
# This line gets the values from the StringVars, converts them to ints,
# and returns them to their respective variables.
try:
readA, readB, readC = [int(val.get()) for val in vals]
except ValueError:
messagebox.showerror(title="Number Error", message='Values must be numbers')
return
# Here the variables are checked to see if they are 0
# Since each one is being checked if it is 0, there is no need to check if they are all 0.
for val in (readA, readB, readC):
if val == 0:
# If they are 0, shows an error message
messagebox.showerror(title="Zero Error", message='Values must not be zero')
return
# Creates a toplevel to display the results
messagewindow = tk.Toplevel()
messagewindow.title('Roots of the equation')
messagewindow.config(bg='#aaf0d1')
negroot = (readB**2)-(4*readA*readC)
quadformulaplus = (-readB + (pow(negroot,0.5)))/(2*readA) #quad forumla
quadformulaminus = (-readB - (pow(negroot,0.5)))/(2*readA) #quad forumla
tk.Label(messagewindow,
text = f'The roots are {quadformulaplus:.1f} and {quadformulaminus:.1f}',
bg='#aaf0d1',
font = ('verdana')).pack(padx = 5, pady = 2)
tk.Button(messagewindow,
text='Close',
command = messagewindow.destroy, # There is no need for a lambda for this.
font = ('verdana'),
bg = '#aaf0d1',
highlightbackground='#aaf0d1').pack(padx = 5, pady = 2)
# print(f'the roots are {quadformulaplus:.1f} and {quadformulaminus:.1f}')
messagewindow.lift() # This is a method of bringing a window to the front
def startup():
startpage = tk.Tk()
startpage.title('Solver')
# COMMENTED OUT FOR TESTING
#photo = tk.PhotoImage(file = r"/Users/isa/Desktop/DiffEqns/cover.png")  #image load
coverbutton = tk.Button(startpage,
# COMMENTED OUT FOR TESTING
#image = photo,
text = "TESTING", # HERE FOR TESTING
highlightbackground='#aaf0d1',
command = lambda root = startpage: mainwindow(root)).pack() # Passes the startpage to the mainwindow function.
startpage.mainloop() # The only mainloop you need.
startup()

Answer 2

我建议首先提高if-else语句的可读性。

coefficients = [readA, readB, readC]
if sum(coefficients):        # If they all are all zeros this will be False
if min(coefficients):    # If any one is zero, this will be False
label = tk.Label(messagewindow, text = f'The roots are {quadformulaplus:.1f} and {quadformulaminus:.1f}', bg='#aaf0d1', font = ('verdana'))
label.grid(row=1)
closebutton = tk.Button(messagewindow, text='Close', command = lambda: messagewindow.destroy(), font = ('verdana'), highlightbackground='#aaf0d1')
closebutton.grid(row=2)
closebutton.config(bg='#aaf0d1')
else:
errorwindow = tk.messagebox.showerror(message='none').pack()
else:
errorwindow = tk.messagebox.showerror(message='none').pack()