On 12/18/19 9:17 AM, Jouk Jansen wrote:
Hi All,
I'm strugling with the C-function mktime. According to the man-pages it
returns "seconds since the Epoch". I tried to use this functions to get
differnces from two date-times , but was could not interpret the result.
When trying to get the diffrence between 30 Nov 2019 23:59:59 and 1 Dec 2019
00:00:00 (see code below) I expected to find 1 second difference but I find:
1577746799 1577833200 -86401
As output of the sample program. (and not 1577833199 1577833200 -1)
How should I read "seconds since the Epoch"????
Is the output of mktime correct?
(I also tried 31 Nov and got the expected 1 second)
(should mktime not give an error for 31 Nov??)
Regards
Jouk
Code :
#include <stdio.h>
#include <time.h>
main()
{
struct tm time_str , time_str2;
time_str.tm_sec = 59; //30 Nov 2019 23:59:59
time_str.tm_min = 59;
time_str.tm_hour = 23;
time_str.tm_mday = 30;
time_str.tm_mon = 11;
time_str.tm_year = 119;
time_str.tm_isdst = 0;
time_str2.tm_sec = 0; // 1 Dec 2019 00:00:00
time_str2.tm_min = 0;
time_str2.tm_hour = 0;
time_str2.tm_mday = 1;
time_str2.tm_mon = 12;
time_str2.tm_year = 119;
time_str2.tm_isdst = 0;
printf( "%d %d %d\n" , mktime( &time_str ) , mktime( &time_str2 ) ,
mktime( &time_str ) - mktime( &time_str2 ) );
}
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Epistularum ad Atticum 7.1.4.3)
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Jouk Jansen
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The month value range is 0 to 11, not 1 to 12. You're calculating
12/30/2019 at 23:59:59 to 01/01/2020 at 00:00:00, or 86401 seconds.
*Mark C. Allman, PMP, CSM*
Founder, See How You Ski, www.seehowyouski.com <http://www.seehowyouski.com>
Sr. Project Manager, Allman Professional Consulting, Inc.,
www.allmanpc.com <http://www.allmanpc.com>
617-947-4263, Twitter: @allmanpc
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