C Exercises: Convert a time_t object to calendar time expressed as Coordinated Universal Time

C Date Time: Exercise-6 with Solution

Write a program in C to convert a time_t object to calendar time expressed as Coordinated Universal Time.

Sample Solution:

C Code:

#define __STDC_WANT_LIB_EXT1__ 1 // Macro definition to request C11 library features
#include <stdio.h>
#include <time.h>

int main(void) {
    time_t t = time(NULL); // Get the current calendar time

    // Print the calendar time expressed as Coordinated Universal Time (UTC) and local time
    printf("\nThe calendar time expressed as Coordinated Universal Time is :");
    printf("\nUTC:   %s", asctime(gmtime(&t))); // Convert and print UTC time using gmtime() and asctime()
    printf("local: %s\n", asctime(localtime(&t))); // Convert and print local time using localtime() and asctime()

#ifdef __STDC_LIB_EXT1__
    struct tm buf;
    char str[26];

    // Convert UTC time using gmtime_s() and asctime_s(), and print the formatted string
    asctime_s(str, sizeof str, gmtime_s(&t, &buf));
    printf("UTC:   %s", str);

    // Convert local time using localtime_s() and asctime_s(), and print the formatted string
    asctime_s(str, sizeof str, localtime_s(&t, &buf));
    printf("local: %s", str);
#endif

    return 0;
}

Sample Output:

The calendar time expressed as Coordinated Universal Time is :
UTC:   Thu Aug 03 10:53:03 2017
local: Thu Aug 03 16:23:03 2017

N.B.: The result may varry for your current system date and time.

Flowchart:

C Programming Code Editor:

Previous: Write a program in C to convert a tm object to custom wide string textual representation.
Next: Write a program in C to convert a time_t object to calendar time expressed as local time.