How to Make a Countdown Timer in C++?

In C++, countdown timers are valuable components in various applications, aiding in scheduling events, controlling timeouts, or displaying the remaining time. In this article, we will learn how to make a countdown timer in C++.

Example:

Input: 
Enter Total Number of Seconds for Countdown Timer: 3

Output: 
Time Remaining: 3
Time Remaining: 2 
Time Remaining: 1 
Time's Up!

Count-Down Timer in C++

To make a countdown timer we can use the <ctime> library, in C++ to fetch the date and time. Combine it with the std::this_thread::sleep_for() function from <thread> along with chrono::seconds(timePeriod) to have the program pause, for a given period of time.

Approach

• Take the user input for the total number of seconds for the counter.
• Loop until the counter is 0 and print the counter value along with current date and time.
• Make the program wait for one second before the next iteration of the loop. By using std::this_thread::sleep_for(chrono::seconds(1)).
• Keep decrementing the value of counter by one.
• Repeat steps 2-4 until the counter value is less than or equal to zero.

C++ Program to Create a Countdown Timer

The below program demonstrates how we can create a countdown timer in C++.

// C++ program to create a countdown timer
#include <chrono>
#include <ctime>
#include <iostream>
#include <thread>
using namespace std;

// Function to get the current date and time as a string.
string getPresentDateTime()
{
    // Declare a time_t variable to hold the current time.
    time_t tt;
    // Declare a pointer to a tm struct to hold the local
    // time.
    struct tm* st;

    // Get the current time.
    time(&tt);
    // Convert the current time to local time.
    st = localtime(&tt);
    // Return the local time as a string.
    return asctime(st);
}

int main()
{
    // Declare an integer variable to hold the total number
    // of seconds for the counter.
    int seconds;

    // Prompt the user to enter the total number of seconds
    // for the counter.
    cout << "Enter total number seconds for the counter"
         << endl;
    cin >> seconds;

    // Loop until the counter reaches zero.
    while (seconds >= 1) {
        // Print the current value of the counter along with
        // the present date and time.
        cout << "Time Remaining : " << seconds
             << " : " + getPresentDateTime() << endl;

        // Pause the program execution for 1 second.
        this_thread::sleep_for(chrono::seconds(1));

        // Decrement the counter.
        seconds--;
    }
    cout << "Time's Up!" << endl;

    return 0;
}

Output

Enter total number seconds for the counter
5
Time Remaining : 5 : Sun May 26 18:24:30 2024
Time Remaining : 4 : Sun May 26 18:24:31 2024
Time Remaining : 3 : Sun May 26 18:24:32 2024
Time Remaining : 2 : Sun May 26 18:24:33 2024
Time Remaining : 1 : Sun May 26 18:24:34 2024
Time's Up!

Time Complexity: O(n), where n is the countdown duration in seconds.
Auxiliary Space: O(1)