strptime does not works with timezone format specifier

Question

I am new to c and trying out on strptime function, which converts string time to structure tm. After converting i am not getting right time. everything is fine but year is displaying wrong(default year 1900).

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

int main()
{
    struct tm tm;
    char *pszTemp = "Mon Apr 25 09:53:00 IST 2016";
    char szTempBuffer[256];

    memset(&tm, 0, sizeof(struct tm));
    memset(szTempBuffer, 0, sizeof(szTempBuffer));
    strptime(pszTemp, "%a %b %d %H:%M:%S %Z %Y", &tm);
    strftime(szTempBuffer, sizeof(szTempBuffer), "%Y-%m-%d %H:%M:%S", &tm);

    printf("Last Boot Time after parsed = %s\n", szTempBuffer);

    return 0;
}

Output : 1900-04-25 09:53:00

Have you checked what [`strptime`](http://man7.org/linux/man-pages/man3/strptime.3.html) returns? So that it doesn't return a `NULL` pointer? — Some programmer dude, Apr 26 '16 at 12:54
@JoachimPileborg: it returns NULL. could you tell the reason/solution?? — Ravi Bhushan, Apr 26 '16 at 17:03
What is your platform? I tried on debian 8.2 gcc 4.9 and all works well. — LPs, Apr 26 '16 at 17:59

score 1 · Answer 1 · edited May 23 '17 at 11:52

As you can see into time.h source file you have to declare __USE_XOPEN and _GNU_SOURCE before to include time.h

#define __USE_XOPEN
#define _GNU_SOURCE

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

int main()
{
    struct tm tm;
    char *pszTemp = "Mon Apr 25 09:53:00 IST 2016";
    char szTempBuffer[256];

    memset(&tm, 0, sizeof(struct tm));
    memset(szTempBuffer, 0, sizeof(szTempBuffer));
    strptime(pszTemp, "%a %b %d %H:%M:%S %Z %Y", &tm);
    strftime(szTempBuffer, sizeof(szTempBuffer), "%Y-%m-%d %H:%M:%S", &tm);

    printf("Last Boot Time after parsed = %s\n", szTempBuffer);

    return 0;
}

You can also simply add definition into you gcc command:

gcc -Wall test.c -o test -D__USE_XOPEN -D_GNU_SOURCE

EDIT

This historical SO post gives all infos about those defines.

@2501 [This historical SO post](http://stackoverflow.com/questions/5378778/what-does-d-xopen-source-do-mean) gives all infos about those defines. — LPs, Apr 26 '16 at 13:11

score 0 · Answer 2 · answered Apr 26 '16 at 13:12

0

The %Z doesn't work for strptime, only for strftime. strptime stops reading after %Z. Therefore the 2016 is missing.

http://linux.die.net/man/3/strptime

If you use glibc it should work.

answered Apr 26 '16 at 13:12

kbnl83

1
1

play a little bit around with the position of %Z and 2016 and you can see it – kbnl83 Apr 26 '16 at 13:21

strptime does not works with timezone format specifier

2 Answers2