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);
}