Introduction

A Flash Sale is a limited-time promotion where items are offered at a discounted price.
To make the sale more exciting and time-sensitive, we can implement a countdown timer
that displays the remaining time until the sale ends. In this tutorial, we will write
a simple Flash Sale Countdown Timer in C programming that will display a live countdown
to a given target time, allowing customers to know how much time is left to grab the
deals before they expire.

Objective

The objective of this project is to implement a countdown timer in C programming
that simulates the countdown for a Flash Sale. It will display the remaining time
in hours, minutes, and seconds, and will update every second until the timer reaches zero.

C Program Code


#include
#include

void flashSaleTimer(int targetTime) {
time_t startTime, currentTime;
int remainingTime;

// Get current time
time(&startTime);

// Start countdown loop
while(1) {
// Get the current time
time(&currentTime);

// Calculate remaining time
remainingTime = targetTime – difftime(currentTime, startTime);

// Check if the sale has ended
if (remainingTime <= 0) {
printf(“The Flash Sale has ended!\n”);
break;
}

// Calculate hours, minutes, and seconds
int hours = remainingTime / 3600;
int minutes = (remainingTime % 3600) / 60;
int seconds = remainingTime % 60;

// Display countdown timer
printf(“\rTime left: %02d:%02d:%02d”, hours, minutes, seconds);

// Wait for 1 second before updating
sleep(1);
}
}

int main() {
// Target time for the flash sale in seconds (e.g., 2 hours = 7200 seconds)
int targetTime = 7200; // Change this value to set your target time for the sale

printf(“Flash Sale Timer\n”);
flashSaleTimer(targetTime);

return 0;
}

Program Explanation

This C program uses the standard time library to calculate and display the remaining
time for a flash sale. Here is a breakdown of how the program works:

• time(): This function is used to get the current system time.
• difftime(): It calculates the difference between the current time
  and the start time of the countdown.
• sleep(1): This makes the program wait for 1 second before updating
  the timer again.
• The program runs a loop where it continuously calculates and displays the time left
  in the format HH:MM:SS until the target time is reached.
• Once the target time is zero, the program displays a message indicating the end of
  the Flash Sale.

How to Run the Program

1. Save the C program to a file (e.g., flash_sale_timer.c).
2. Open your terminal or command prompt.
3. Navigate to the folder where the file is saved.
4. Compile the program using a C compiler. For example, use GCC:

   gcc flash_sale_timer.c -o flash_sale_timer

5. Run the program:

   ./flash_sale_timer

6. The countdown timer will start and display the remaining time until the Flash Sale ends.