alarm_clock.py

from tkinter import *
import time
import os

quitting = False
alarm_state = False

def quitter(): # function controls how the application should close
    global quitting
    quitting = True

win = Tk()
win.title("Clock")
win.protocol("WM_DELETE_WINDOW", quitter) ## runs the function when the X button is pressed.

example = Label(win,font=('times', 28, 'bold'), background='blue', foreground='white')
example.pack(fill=BOTH, expand=1)
e1=Entry(win)
e1.pack()

def button():
    global alarm_state
    alarm_state = True

bt=Button(win, text='Set alarm', command=button).pack()

def check_alarm(settime):
    global alarm_state
    if settime.get()==time.strftime('%H:%M:%S') and alarm_state:
        print("Times Up!")
        alarm_state = False

while not quitting:
    win.update()
    win.update_idletasks()
    example["text"]  = time.strftime('%H:%M:%S')
    check_alarm(e1)