mainloop() function in python

Question

I am confused about where to put the mainloop function in python. When I use this code:

from tkinter import *
import sys
window = Tk()
def mainFunct():
    while True:

        label = Label(window,text="Hello World")
        label2 = Label(window, text = "Hello World2")
        menu = input("Please input something")
        if menu == "a":
            label.pack()
        if menu == "b":
            label2.pack()
        if menu == "c":
            sys.exit()

        window.mainloop()
mainFunct()

I want label to be packed when the user inputs a and when the user inputs b i want label2 to be packed. I am not sure when and why to use mainloop. Right now when I run the program, the GUi only pops up after I have inputted something and then I can't even input anything else and I think it has some thing to do with the window.mainloop() function because it just loops over and over again instead of running the while True loop again.

Leb · Accepted Answer · 2015-06-14 03:16:16Z

1

I was able to understand your question better based off of the comment. Let me know if this is what you're looking for:

import tkinter as tk

class HelloWorld(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.entry = tk.Entry(self)
        self.button = tk.Button(self, text="What's your input?", command=self.on_button)
        self.button.pack()
        self.entry.pack()

    def on_button(self):
        answer = self.entry.get()
        if answer == "a":
            print("Hello World")
        elif answer == "b":
            print("Hello World 2")
        elif answer == "c":
            root.destroy()

root = HelloWorld()
root.mainloop()

So when dealing with the input of a user it's better to create a class and from that obtain/compare the information.

Now if the answer is anything other than a, b, or c there will be no response from the program, so adjust accordingly.

edited Jun 14, 2015 at 3:16

answered Jun 13, 2015 at 23:55

Leb

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1 Comment

mre12345 Over a year ago

Thanks for the response!, I have either way I put the mainloop() it will just loop infinitely... so if I have it before the mainFunct then it will just show the screen and if I have it other the mainFunct() then the labels will only pack after I type in "c". E.g. 'code' mainFunct() root.mainloop() 'code' The GUI interface will only pop up after the mainFunction but how do I pack things when I want the mainFunction to loop?

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