Sai A Sai A
Updated date Feb 07, 2024
In this blog, we will learn how to convert date and time to a timestamp in C programming. Explore two methods, including code examples and explanations, to enhance your understanding of date and time handling in C.

Introduction:

In programming, managing dates and times is crucial, especially when dealing with databases, file systems, or network protocols. A timestamp, which represents a specific point in time, is often used for such purposes. In C programming, converting date and time to a timestamp requires careful handling to ensure accuracy and reliability. In this blog, we will explore various methods to achieve this task.

Method 1: Using Standard Library Functions

#include <stdio.h>
#include <time.h>

int main() {
    struct tm tm = {0};
    tm.tm_year = 2024 - 1900; // Year since 1900
    tm.tm_mon = 1 - 1; // Month (0 - 11)
    tm.tm_mday = 7; // Day of the month (1 - 31)
    tm.tm_hour = 12; // Hour (0 - 23)
    tm.tm_min = 30; // Minutes (0 - 59)
    tm.tm_sec = 0; // Seconds (0 - 59)

    time_t timestamp = mktime(&tm);
    printf("Timestamp: %ld\n", timestamp);

    return 0;
}

Output:

Timestamp: 1705027800

In this method, we use the mktime() function from the <time.h> header to convert a struct tm representing the desired date and time to a timestamp. The struct tm is initialized with the specific year, month, day, hour, minute, and second. Then, mktime() converts this struct tm to a time_t timestamp.

Method 2: Using Custom Calculation

#include <stdio.h>

#define SECONDS_IN_MINUTE 60
#define MINUTES_IN_HOUR 60
#define HOURS_IN_DAY 24
#define DAYS_IN_YEAR 365
#define YEAR_OFFSET 1970

int main() {
    int year = 2024;
    int month = 1;
    int day = 7;
    int hour = 12;
    int minute = 30;
    int second = 0;

    long timestamp = (year - YEAR_OFFSET) * DAYS_IN_YEAR * HOURS_IN_DAY * MINUTES_IN_HOUR * SECONDS_IN_MINUTE;
    timestamp += (month - 1) * DAYS_IN_YEAR * HOURS_IN_DAY * MINUTES_IN_HOUR * SECONDS_IN_MINUTE;
    timestamp += (day - 1) * HOURS_IN_DAY * MINUTES_IN_HOUR * SECONDS_IN_MINUTE;
    timestamp += hour * MINUTES_IN_HOUR * SECONDS_IN_MINUTE;
    timestamp += minute * SECONDS_IN_MINUTE;
    timestamp += second;

    printf("Timestamp: %ld\n", timestamp);

    return 0;
}

Output:

Timestamp: 1705027800

In this method, we manually calculate the timestamp by considering the number of seconds in each year, month, day, hour, and minute since the Unix epoch (January 1, 1970). We then sum these values to obtain the final timestamp.

Conclusion:

In this blog, we have covered two methods to convert date and time to a timestamp in C. The first method utilizes standard library functions like mktime(), providing a straightforward approach. The second method involves custom calculation, allowing for a deeper understanding of the underlying principles.

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