Stopwatch in Python

In Python you can use the time module to wait (you can also get the time and date). To be explicit, the time module provides various time-related functions.

This is very useful for many applications. If you make a game, it should not update every millisecond. If you make weather station software, it makes no sense to update in such a short time. For an alarm clock app, you need it to wait.

Lets say you want to make a stopwatch, without the program pausing there would be no way to create one.

Sleep function

The module time has a function named sleep, which pauses the program (it complete freezes the program).

time.sleep(t)

This waits for t number of seconds. Consider this program which waits for one second before it outputs the next word.

import time.sleep

print("Hello")
time.sleep(1)
print("World")

Stopwatch

So you can use the time.sleep() function to pause the program. But a stopwatch doesn't have a limit, it needs to go on. For that, you can use a while loop. Then you can use Ctrl+c to exit the program.

import time

while True:
    print("Clock ticks")
    time.sleep(1)

If you run the above program it outputs:

➜  ~ python3 stopwatch.py
Clock ticks
Clock ticks
Clock ticks

Until you press Ctrl+c. Now it needs to count seconds, you can use time.time() to get the current time.

The example below will output every second passed until Ctrl+C is passed.

import time

start = time.time()
while True:
    time.sleep(1)
    total_secs = round(time.time() - start)
    print(total_secs)

Formatting

To format it you can use f-strings with two digits. With a simple calculation you can get the minutes and seconds.

import time

start = time.time()
while True:
    time.sleep(1)
    total_secs = round(time.time() - start)
    minute = round(total_secs / 60)
    seconds = round(total_secs % 60)
    s = f"{minute:02d}:{seconds:02d}"
    print(s)

Related links:

• The time module
• Learn Python