Re: What does mktime return????
On Wed, Dec 18, 2019 at 1:46 PM John Pilkington wrote: > On 18/12/2019 15:12, Mark C. Allman wrote: > > > > 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. > > > > This is in accord with 'man mktime' but it's certainly a trap for the > unwary. Calendar days are treated normally, but not months. I wonder > how many space probes have strayed or contracts misfired... > There are two hard things in computer science: cache invalidation, naming things, and off-by-one errors. :) G -- Grant Gainey Principal Software Engineer, Red Hat System Management Engineering ___ users mailing list -- users@lists.fedoraproject.org To unsubscribe send an email to users-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org
Re: What does mktime return????
On 18/12/2019 15:12, Mark C. Allman wrote: 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 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. This is in accord with 'man mktime' but it's certainly a trap for the unwary. Calendar days are treated normally, but not months. I wonder how many space probes have strayed or contracts misfired... Changing it now would cause yet more confusion. John P ___ users mailing list -- users@lists.fedoraproject.org To unsubscribe send an email to users-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org
Re: EXTERNAL: Re: What does mktime return????
On 12/18/19 10:24 AM, Walter H. wrote:
Hello,
I tried your programme on my system (other linux distribution), and got the
same result;
even on windows the same results;
but this is interesting
# date --date="Dec 1 00:00:00 2019" +"%s"
1575154800
# date --date="Nov 30 23:59:59 2019" +"%s"
1575154799
there you have this 1 second difference;
I'd say mktime seens to be buggy ...
Walter
On 18.12.2019 15:17, 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
#include
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 ) );
}
remember that the month values (tm_mon) go from 0 to 11.
change tm_mon for November to 10 and for December to 11 and you get the
expected result.
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Re: What does mktime return????
Hello,
I tried your programme on my system (other linux distribution), and got
the same result;
even on windows the same results;
but this is interesting
# date --date="Dec 1 00:00:00 2019" +"%s"
1575154800
# date --date="Nov 30 23:59:59 2019" +"%s"
1575154799
there you have this 1 second difference;
I'd say mktime seens to be buggy ...
Walter
On 18.12.2019 15:17, 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
#include
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 ) );
}
smime.p7s
Description: S/MIME Cryptographic Signature
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Re: What does mktime return????
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
#include
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 ) );
}
Pax, vel iniusta, utilior est quam iustissimum bellum.
(free after Marcus Tullius Cicero (106 b.Chr.-46 b.Chr.)
Epistularum ad Atticum 7.1.4.3)
Touch not the cat bot a glove
--<
Jouk Jansen
jo...@hrem.nano.tudelft.nl
Technische Universiteit Delfttt uu uu ddd
Kavli Institute of Nanoscience tt uu uu dddd
Nationaal centrum voor HREM tt uu uu dd dd
Lorentzweg 1 tt uu uu dd dd
2628 CJ Delfttt uu uu dd dd
Nederlandtt uu uu dddd
tel. 31-15-2782272 tt uuu ddd
--<
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
Sr. Project Manager, Allman Professional Consulting, Inc.,
www.allmanpc.com
617-947-4263, Twitter: @allmanpc
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What does mktime return????
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
#include
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 ) );
}
Pax, vel iniusta, utilior est quam iustissimum bellum.
(free after Marcus Tullius Cicero (106 b.Chr.-46 b.Chr.)
Epistularum ad Atticum 7.1.4.3)
Touch not the cat bot a glove
>--<
Jouk Jansen
jo...@hrem.nano.tudelft.nl
Technische Universiteit Delfttt uu uu ddd
Kavli Institute of Nanoscience tt uu uu dddd
Nationaal centrum voor HREM tt uu uu dd dd
Lorentzweg 1 tt uu uu dd dd
2628 CJ Delfttt uu uu dd dd
Nederlandtt uu uu dddd
tel. 31-15-2782272 tt uuu ddd
>--<
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