C Epoch Converter Routines - JohnHau/mis GitHub Wiki

Convert from epoch to human-readable date How to convert epoch / UNIX timestamps to normal readable date/time using C.

Example C routine using STRFTIME. STRFTIME converts information from a time structure to a string form, and writes the string into the memory area pointed to by "string".

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

int main(void) { time_t now; struct tm ts; char buf[80];

// Get current time
time(&now);

// Format time, "ddd yyyy-mm-dd hh:mm:ss zzz"
ts = *localtime(&now);
strftime(buf, sizeof(buf), "%a %Y-%m-%d %H:%M:%S %Z", &ts);
printf("%s\n", buf);
return 0;

} For more information on strftime click here.

With a custom epoch (here 1262304000):

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

int main(void) { time_t rawtime = 1262304000; struct tm ts; char buf[80];

// Format time, "ddd yyyy-mm-dd hh:mm:ss zzz"
ts = *localtime(&rawtime);
strftime(buf, sizeof(buf), "%a %Y-%m-%d %H:%M:%S %Z", &ts);
printf("%s\n", buf);
return 0;

}

Convert from human-readable date to epoch #include <stdio.h> #include <time.h>

int main(void) { struct tm t; time_t t_of_day;

t.tm_year = 2019-1900;  // Year - 1900
t.tm_mon = 7;           // Month, where 0 = jan
t.tm_mday = 8;          // Day of the month
t.tm_hour = 16;
t.tm_min = 11;
t.tm_sec = 42;
t.tm_isdst = -1;        // Is DST on? 1 = yes, 0 = no, -1 = unknown
t_of_day = mktime(&t);

printf("seconds since the Epoch: %ld\n", (long) t_of_day);

} Thanks to random_dude.