Example: Calculating the Difference Between Two Time Periods in C

// Calculating the Difference Between Two Time Periods in C
#include <stdio.h>
#include <time.h>

// The main function of the program
int main()
{
    // Step-1 Declare and initialize time variables
    struct tm time1 = {0};  // Initializing time1 to zero
    struct tm time2 = {0};  // Initializing time2 to zero

    // Step-2 Input the first time period (time1)
    time1.tm_year = 2025 - 1900;  // tm_year is year since 1900
    time1.tm_mon = 4;             // Month is 0-based (0 = January)
    time1.tm_mday = 1;            // Day of the month
    time1.tm_hour = 10;           // Hour (24-hour format)
    time1.tm_min = 30;            // Minutes
    time1.tm_sec = 0;             // Seconds

    // Step-3 Input the second time period (time2)
    time2.tm_year = 2025 - 1900;
    time2.tm_mon = 4;
    time2.tm_mday = 9;
    time2.tm_hour = 15;
    time2.tm_min = 45;
    time2.tm_sec = 0;

    // Step-4 Convert struct tm to time_t for both time periods
    time_t t1 = mktime(&time1);
    time_t t2 = mktime(&time2);

    // Step-5 Calculate the difference in seconds
    double difference = difftime(t2, t1);

    // Step-6 Convert the difference to hours, minutes, and seconds
    int hours = difference / 3600;  // 3600 seconds in an hour
    int minutes = (difference - (hours * 3600)) / 60;  // Remaining minutes
    int seconds = difference - (hours * 3600) - (minutes * 60);  // Remaining seconds

    // Step-7 Output the result
    printf("\nTime difference: %d hours, %d minutes, %d seconds\n", hours, minutes, seconds);

    return 0;
}