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Absolute madness with managing time in C

if (row  = mysql_fetch_row(res))
    {
        assert(atoi(row[0]) == contest_id);
        time_t start_time = atoi(row[1]);
        time_t stop_time  = atoi(row[4]);
        int duration = atoi(row[3]);

        struct tm cur_time_tm;
        struct tm start_time_tm;
        struct tm stop_time_tm;

        strncpy(sstart_time, row[1], sizeof(sstart_time));
        strncpy(sstop_time, row[4], sizeof(sstop_time));

        strptime(sstop_time, "%Y-%m-%d %H:%M:%S", &stop_time_tm);
        strptime(sstart_time,  "%Y-%m-%d %H:%M:%S", &start_time_tm);

        printf("ascstarttime=%s;ascstop%s;\n", asctime(&start_time_tm), asctime(&stop_time_tm));
        printf("startstr=%s;stopstr=%s\n", sstart_time, sstop_time);

        start_time = mktime(&start_time_tm);
        stop_time = mktime(&stop_time_tm);

        printf("mkstart=%s;mkstop=%s\n", ctime(&start_time), ctime(&stop_time));
}

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Output:

ascstarttime=Sat Jan 1 04:00:01 2000
;ascstopSat Jan 1 04:00:01 2000
;
startstr=2000-01-01 04:00:01;stopstr=2000-01-01 09:00:01
mkstart=Sat Jan 1 04:00:01 2000
;mkstop=Sat Jan 1 04:00:01 2000

why asctime(&stop_time_tm) gives Sat Jan 1 04:00:01 2000
but sstop_time outputs 2000-01-01 09:00:01
?

why sstart_time, sstop_time are different
but start_time_tm, stop_time_tm are always the same.
How?

Zoppo

Hi ,

I think the problem is how you use the asctime because this uses an internal buffer which means calling it a second time will seemingly 'change' the result of the first call - see i.e. http://www.cplusplus.com/reference/ctime/asctime/, there you can find as note The returned value points to an internal array whose validity or value may be altered by any subsequent call to asctime or ctime.

Try to replace this line

        printf("ascstarttime=%s;ascstop%s;\n", asctime(&start_time_tm), asctime(&stop_time_tm));

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with this code

        printf("ascstarttime=%s;", asctime(&start_time_tm));
        printf("ascstop%s;\n", asctime(&stop_time_tm));

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to find out if this is the problem.

Hope that helps,

ZOPPO

Nusrat Nuriyev

ASKER

No.
Generally, second strptime call returns NULL. So, probably, asctime is not an issue.

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Zoppo

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Nusrat Nuriyev

ASKER

However, that was not a solution, this information is useful.
I remembered, the problem was in memory management with standard alloca function, there were absolutely wrong memory allocations.