CODEWITHSUNDEEP
cepochtime.h
Miguel
Miguel

Reputation: 408

Get epoch seconds for specific date in C

How can I get the number of seconds passed since January 1, 1970 for a specific date, for example:"2017-09-14 23:24:46"

#include <stdio.h>
#include <stdint.h>
#include <time.h>
int main()
{

    struct tm tmVar;
    time_t timeVar;
    sscanf("2017-09-14 23:24:46","%d-%d-%d %d:%d:%d",&tmVar.tm_year
                        ,&tmVar.tm_mon, &tmVar.tm_mday,
                         &tmVar.tm_hour, &tmVar.tm_min, 
                         &tmVar.tm_sec);
     tmVar.tm_isdst = 1;
     printf("tm_year :%d\n",tmVar.tm_year);
     printf("tm_month :%d\n",tmVar.tm_mon);
     printf("tm_day :%d\n",tmVar.tm_mday);
     printf("tm_hour :%d\n",tmVar.tm_hour);
     printf("tm_min :%d\n",tmVar.tm_min);
     printf("tm_sec :%d\n",tmVar.tm_sec);
     timeVar = mktime(&tmVar);
     printf("time %d\n",timeVar);
 }

The output however is not what I expect:

tm_year :2017

tm_month :9

tm_day :14

tm_hour :23

tm_min :24

tm_sec :46

time 1336625342

According to epochconverter.com, the proper value should be 1510529086. Why am I not getting this value?

Upvotes: 1

Views: 3257

Answers (1)

dbush
dbush

Reputation: 223699

You need to adjust the values stored in your struct.

The tm_year field is years since 1900, so subtract 1900 from this value.

The tm_mon field is months since January, so subtract 1 from this value.

So do the following after populating the struct:

 tmVar.tm_year -= 1900;
 tmVar.tm_mon--;

Output:

tm_year :117
tm_month :8
tm_day :14
tm_hour :23
tm_min :24
tm_sec :46
time 1505445886

Upvotes: 3

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