Create a stopwatch using python

This article focus on creating a stopwatch using Tkinter in python 
Tkinter : Tkinter is the standard GUI library for Python. Python when combined with Tkinter provides a fast and easy way to create GUI applications. Tkinter provides a powerful object-oriented interface to the Tk GUI toolkit. It’s very easy to get started with Tkinter, here are some sample codes to get your hands on Tkinter in python. 

Python3

# Python program to create a
# a new window using Tkinter
# importing the required libraries
import tkinter

# creating a object 'top' as instance of class Tk
top = tkinter.Tk()

# This will start the blank window
top.mainloop()

Output:

Creating Stopwatch using Tkinter

Now lets try to create a program using Tkinter module to create a stopwatch. 
A stopwatch is a handheld timepiece designed to measure the amount of time elapsed from a particular time when it is activated to the time when the piece is deactivated. A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stop clock. In manual timing, the clock is started and stopped by a person pressing a button. In fully automatic time, both starting and stopping are triggered automatically, by sensors. 
Required Modules: We are only going to use Tkinter for creating GUI and no other libraries will be used in this program.
Source Code:

Python3

# Python program to illustrate a stop watch
# using Tkinter
#importing the required libraries
import tkinter as Tkinter
from datetime import datetime
counter = 66600
running = False
def counter_label(label):
    def count():
        if running:
            global counter

            # To manage the initial delay.
            if counter==66600:
                display="Starting..."
            else:
                tt = datetime.fromtimestamp(counter)
                string = tt.strftime("%H:%M:%S")
                display=string

            label['text']=display   # Or label.config(text=display)

            # label.after(arg1, arg2) delays by
            # first argument given in milliseconds
            # and then calls the function given as second argument.
            # Generally like here we need to call the
            # function in which it is present repeatedly.
            # Delays by 1000ms=1 seconds and call count again.
            label.after(1000, count)
            counter += 1

    # Triggering the start of the counter.
    count()

# start function of the stopwatch
def Start(label):
    global running
    running=True
    counter_label(label)
    start['state']='disabled'
    stop['state']='normal'
    reset['state']='normal'

# Stop function of the stopwatch
def Stop():
    global running
    start['state']='normal'
    stop['state']='disabled'
    reset['state']='normal'
    running = False

# Reset function of the stopwatch
def Reset(label):
    global counter
    counter=66600

    # If rest is pressed after pressing stop.
    if running==False:
        reset['state']='disabled'
        label['text']='Welcome!'

    # If reset is pressed while the stopwatch is running.
    else:
        label['text']='Starting...'

root = Tkinter.Tk()
root.title("Stopwatch")

# Fixing the window size.
root.minsize(width=250, height=70)
label = Tkinter.Label(root, text="Welcome!", fg="black", font="Verdana 30 bold")
label.pack()
f = Tkinter.Frame(root)
start = Tkinter.Button(f, text='Start', width=6, command=lambda:Start(label))
stop = Tkinter.Button(f, text='Stop',width=6,state='disabled', command=Stop)
reset = Tkinter.Button(f, text='Reset',width=6, state='disabled', command=lambda:Reset(label))
f.pack(anchor = 'center',pady=5)
start.pack(side="left")
stop.pack(side ="left")
reset.pack(side="left")
root.mainloop()

Output:

This article is contributed by Subhajit Saha. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.