Countdown Timer Revision

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Using concepts discussed in previous topics, we will write a “Countdown Timer” that asks the user for a time in seconds, then counts down until we hit zero.

We need to import the “time” module and can use a function within the “time” module called the “sleep” function, which effectively puts the program to sleep for some time.

import time
time.sleep(3)      # <-- sleep function pauses for 3 secs
print("Times Up!")

When we execute this code, nothing happens for 3 seconds, then it prints the output.

To add a visual indication that something is happening:

import time
duration = int(input("Timer duration (in seconds)? "))

for x in range(0, duration):  # <-- increments
    print(x)
    time.sleep(1)

print("Times Up!")

but this is counting in the wrong direction.

Reverse the countdown by changing the “for loop” to decrement from the user inputted value:

import time
duration = int(input("Timer duration (in seconds)? "))

for x in range(duration, 0, -1): # <-- decrements
    print(x)
    time.sleep(1)

print("Times Up!")

To change the format to a digital clock countdown appearance: 00:05:23

import time
duration = int(input("Timer duration (in seconds)? "))

for x in range(duration, 0, -1):
    seconds = x
    print(f"00:00:{seconds}")
    time.sleep(1)

print("Times Up!")

If we enter 70 seconds for the duration, it will show as 70. We don’t want to see a number bigger than 60 so we can use the “modulus” feature to show remainder after dividing by 60.

import time
duration = int(input("Timer duration (in seconds)? "))

for x in range(duration, 0, -1):
    seconds = x % 60  # <-- modulus: only shows the remainder
    print(f"00:00:{seconds:02}") # <-- 2 digits, 0 padded
    time.sleep(1)

print("Times Up!")

We should assign minutes, hours and possibly days if the program required it.

import time
duration = int(input("Timer duration (in seconds)? "))

for x in range(duration, 0, -1):
    seconds = x % 60  # <-- modulus: only shows the remainder
    minutes = int(x / 60)
    # minutes = x // 60
    hours = int(x / 3600)
    print(f"{hours}:{minutes:02}:{seconds:02}")
    time.sleep(1)

print("Times Up!")

Advanced

A quick introduction of Python sys.stdin and sys.stdout

sys.stdin and sys.stdout are file objects which are used by the interpreter for standard input and standard output. Data received by raw_input comes from stdin, which is normally connects to the keyboard. stdin can be redirected so that input instead comes from a file. This can be very useful for automating scripts.

About sys.stdout.write() and print() When you call the print(obj) function, it actually calls the sys.stdout.write(obj + ‘\n’) like:

import sys
sys.stdout.write("hello" + "\n")
print("hello")

Our final solution to the countdown timer:

import time
import sys
duration = int(input("Timer duration (in seconds)? "))

for x in range(duration, 0, -1):
    seconds = x % 60  # <-- modulus: only shows the remainder
    minutes = int(x / 60)
    # minutes = x // 60
    hours = int(x / 3600)
    sys.stdout.write(f"\r{hours}:{minutes:02}:{seconds:02}")
    # \r - carriage return – overwrites previous words
    time.sleep(1)

print("\nTimes Up!") # <-- \n new line

Higher End Example using a Function

In this example:

The countdown_timer function takes number of seconds as an argument.
Inside the function, a while loop is used to countdown from the specified number of seconds to zero.
The divmod function is used to get the minutes and seconds from the remaining time.
The timer_format variable is used to format and print the remaining time in MM:SS format.
The time.sleep(1) function is used to pause the program for one second in each iteration.
Countdown is displayed by overwriting previous line using carriage return (\r).
The loop continues until the countdown reaches zero, and then the “Time’s up!” message is printed.

import time
import sys


def countdown_timer():
    try:
        # Get user input for countdown duration in seconds
        duration = int(input("Enter countdown duration in seconds: "))

        # Countdown timer
        while duration:
            mins, secs = divmod(duration, 60)
            timer_format = "{:02d}:{:02d}".format(mins, secs)
            sys.stdout.write("\rTime remaining: {}".format(timer_format))
            sys.stdout.flush()
            time.sleep(1)
            duration -= 1

        print("\nTime's up!")

    except ValueError:
        print("Invalid input. Please enter a valid number of seconds.")


# Run the countdown timer
countdown_timer()

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Countdown Timer Revision

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