# How to convert timestamp to epoch?

Discussion in 'Perl Misc' started by void.no.spam.com@gmail.com, Oct 30, 2007.

1. ### Guest

If I get timestamps in the following format:

22-OCT-07 06.16.44.160000 PM
22-OCT-07 08.16.02.686000 AM

What is the easiest way for me to convert it into the number of
seconds since 1970?

, Oct 30, 2007

2. ### TonyVGuest

On Oct 30, 2:45 pm, ""
<> wrote:
> If I get timestamps in the following format:
>
> 22-OCT-07 06.16.44.160000 PM
> 22-OCT-07 08.16.02.686000 AM
>
> What is the easiest way for me to convert it into the number of
> seconds since 1970?

I would probably make it a function:

use Time::Local;

my \$ts_to_convert = '22-jun-07 06.16.44.160000 PM';
print timestamp_to_epoch(\$ts_to_convert);

sub timestamp_to_epoch {
my (\$ts) = @_;
my %month = ('JAN' => 0, 'FEB' => 1, 'MAR' => 2, 'APR' => 3, 'MAY'
=> 4, 'JUN' => 5,
'JUL' => 6, 'AUG' => 7, 'SEP' => 8, 'OCT' => 9, 'NOV' => 10, 'DEC'
=> 11);
if (\$ts =~ m{^(\d{1,2})-(\w{1,3})-(\d{1,2}) (\d{1,2})\.(\d{1,2})\.
(\d{1,2})\.\d+ ([AP])M\$}i) {
my (\$dd, \$mo, \$yy, \$hh, \$mm, \$ss, \$ap) = (\$1, \$2, \$3, \$4, \$5, \$6,
\$7);
\$yy += 2000; \$mo = \$month{uc(\$mo)};
\$hh += 12 if (uc(\$ap) eq 'P');
return timelocal(\$ss, \$mm, \$hh, \$dd, \$mo, \$yy);
}
else { return 0; }
}

Check to make sure your return value is non-zero, and you're in

You might also want to check out the Date::Manip package, as I
understand that it was designed to do this type of parsing. I don't
use it myself, so I'll defer to others' recommendations for it, but
here it is:
http://search.cpan.org/dist/Date-Manip/Manip.pod

TonyV, Oct 30, 2007

3. ### TonyVGuest

On Oct 30, 3:15 pm, TonyV <> wrote:
> On Oct 30, 2:45 pm, ""
>
> <> wrote:
> > If I get timestamps in the following format:

>
> > 22-OCT-07 06.16.44.160000 PM
> > 22-OCT-07 08.16.02.686000 AM

>
> > What is the easiest way for me to convert it into the number of
> > seconds since 1970?

>
> I would probably make it a function:

Gah, here's a more word-wrap-friendly version:

use Time::Local;

my \$ts_to_convert = '22-jun-07 06.16.44.160000 PM';
print timestamp_to_epoch(\$ts_to_convert);

sub timestamp_to_epoch {
my (\$ts) = @_;
my %month = (
'JAN' => 0, 'FEB' => 1, 'MAR' => 2, 'APR' => 3,
'MAY' => 4, 'JUN' => 5, 'JUL' => 6, 'AUG' => 7,
'SEP' => 8, 'OCT' => 9, 'NOV' => 10, 'DEC' => 11);
my \$regex = '^(\d{1,2})-(\w{1,3})-(\d{1,2}) ';
\$regex .= '(\d{1,2})\.(\d{1,2})\.(\d{1,2})';
\$regex .= '\.\d+ ([AP])M\$';
if (\$ts =~ m{\$regex}i) {
my (\$dd, \$mo, \$yy, \$hh, \$mm, \$ss, \$ap) =
(\$1, \$2, \$3, \$4, \$5, \$6, \$7);
\$yy += 2000; \$mo = \$month{uc(\$mo)};
\$hh += 12 if (uc(\$ap) eq 'P');
return timelocal(\$ss, \$mm, \$hh, \$dd, \$mo, \$yy);
}
else { return 0; }
}

TonyV, Oct 30, 2007
4. ### Paul LalliGuest

On Oct 30, 2:45 pm, ""
<> wrote:
> If I get timestamps in the following format:
>
> 22-OCT-07 06.16.44.160000 PM
> 22-OCT-07 08.16.02.686000 AM
>
> What is the easiest way for me to convert it into the number of
> seconds since 1970?

If you convert those first two periods to colons, Date:arse can
handle it just fine:

#!/usr/bin/perl
use strict;
use warnings;
use Date:arse 'str2time';
my \$date = "22-OCT-07 06.16.44.160000 PM";
\$date =~ s/\./:/ for 1..2;
my \$epoch = str2time(\$date);
print "Epoch: \$epoch\n";
__END__

Paul Lalli

Paul Lalli, Oct 30, 2007
5. ### Guest

On Oct 30, 3:27 pm, TonyV <> wrote:
> On Oct 30, 3:15 pm, TonyV <> wrote:
>
> > On Oct 30, 2:45 pm, ""

>
> > <> wrote:
> > > If I get timestamps in the following format:

>
> > > 22-OCT-07 06.16.44.160000 PM
> > > 22-OCT-07 08.16.02.686000 AM

>
> > > What is the easiest way for me to convert it into the number of
> > > seconds since 1970?

>
> > I would probably make it a function:

>
> Gah, here's a more word-wrap-friendly version:
>
> use Time::Local;
>
> my \$ts_to_convert = '22-jun-07 06.16.44.160000 PM';
> print timestamp_to_epoch(\$ts_to_convert);
>
> sub timestamp_to_epoch {
> my (\$ts) = @_;
> my %month = (
> 'JAN' => 0, 'FEB' => 1, 'MAR' => 2, 'APR' => 3,
> 'MAY' => 4, 'JUN' => 5, 'JUL' => 6, 'AUG' => 7,
> 'SEP' => 8, 'OCT' => 9, 'NOV' => 10, 'DEC' => 11);
> my \$regex = '^(\d{1,2})-(\w{1,3})-(\d{1,2}) ';
> \$regex .= '(\d{1,2})\.(\d{1,2})\.(\d{1,2})';
> \$regex .= '\.\d+ ([AP])M\$';
> if (\$ts =~ m{\$regex}i) {
> my (\$dd, \$mo, \$yy, \$hh, \$mm, \$ss, \$ap) =
> (\$1, \$2, \$3, \$4, \$5, \$6, \$7);
> \$yy += 2000; \$mo = \$month{uc(\$mo)};
> \$hh += 12 if (uc(\$ap) eq 'P');
> return timelocal(\$ss, \$mm, \$hh, \$dd, \$mo, \$yy);
> }
> else { return 0; }
>
>
>
> }

Thank you for writing that up.

I did have to change one line to get it to work:

sub timestamp_to_epoch {
my (\$ts) = @_;
my %month = (
'JAN' => 0, 'FEB' => 1, 'MAR' => 2, 'APR' => 3,
'MAY' => 4, 'JUN' => 5, 'JUL' => 6, 'AUG' => 7,
'SEP' => 8, 'OCT' => 9, 'NOV' => 10, 'DEC' => 11);
my \$regex = '^(\d{1,2})-(\w{1,3})-(\d{1,2}) ';
\$regex .= '(\d{1,2})\.(\d{1,2})\.(\d{1,2})';
\$regex .= '\.\d+ ([AP])M\$';
if (\$ts =~ m{\$regex}i) {
my (\$dd, \$mo, \$yy, \$hh, \$mm, \$ss, \$ap) =
(\$1, \$2, \$3, \$4, \$5, \$6, \$7);
\$yy += 2000; \$mo = \$month{uc(\$mo)};
\$hh += 12 if (uc(\$ap) eq 'P' && \$hh != 12);
return timelocal(\$ss, \$mm, \$hh, \$dd, \$mo, \$yy);
}
else { return 0; }
}

, Oct 30, 2007
6. ### Guest

On Oct 30, 1:27 pm, TonyV <> wrote:
>
> use Time::Local;
>
> my \$ts_to_convert = '22-jun-07 06.16.44.160000 PM';
> print timestamp_to_epoch(\$ts_to_convert);
>
> sub timestamp_to_epoch {
> my (\$ts) = @_;
> my %month = (
> 'JAN' => 0, 'FEB' => 1, 'MAR' => 2, 'APR' => 3,
> 'MAY' => 4, 'JUN' => 5, 'JUL' => 6, 'AUG' => 7,
> 'SEP' => 8, 'OCT' => 9, 'NOV' => 10, 'DEC' => 11);
> my \$regex = '^(\d{1,2})-(\w{1,3})-(\d{1,2}) ';
> \$regex .= '(\d{1,2})\.(\d{1,2})\.(\d{1,2})';
> \$regex .= '\.\d+ ([AP])M\$';
> if (\$ts =~ m{\$regex}i) {
> my (\$dd, \$mo, \$yy, \$hh, \$mm, \$ss, \$ap) =
> (\$1, \$2, \$3, \$4, \$5, \$6, \$7);
> \$yy += 2000; \$mo = \$month{uc(\$mo)};
> \$hh += 12 if (uc(\$ap) eq 'P');
> return timelocal(\$ss, \$mm, \$hh, \$dd, \$mo, \$yy);
> }
> else { return 0; }
> }

Ummm... this code has a subtle error in it: it won't correctly
convert dates with "12" as the hour. To see what I mean, try running

my \$ts_to_convert = '22-JUN-07 12.16.44.160000 PM';

Instead of an epoch time value, you'll see an error message like:

Hour '24' out of range 0..23

Converting 12-hour AM/PM time to 24-hour time (and vice-versa) is a
little trickier than many people think. They often forget to check
the cases where the hour equals 12, thinking that simply adding 12 to
the hour (if they are in PM) is enough to convert from 12-hour to 24-
hour time (like in the code you gave).

But "12:00 am" needs to be converted to "00:00" and "12:00 pm"
needs to be converted to "12:00", and just adding 12 to the hour value
won't correctly convert either.

, Oct 30, 2007
7. ### Guest

Oops, actually this is the working version:

sub timestamp_to_epoch {
my (\$ts) = @_;
my %month = (
'JAN' => 0, 'FEB' => 1, 'MAR' => 2, 'APR' => 3,
'MAY' => 4, 'JUN' => 5, 'JUL' => 6, 'AUG' => 7,
'SEP' => 8, 'OCT' => 9, 'NOV' => 10, 'DEC' => 11);
my \$regex = '^(\d{1,2})-(\w{1,3})-(\d{1,2}) ';
\$regex .= '(\d{1,2})\.(\d{1,2})\.(\d{1,2})';
\$regex .= '\.\d+ ([AP])M\$';
if (\$ts =~ m{\$regex}i) {
my (\$dd, \$mo, \$yy, \$hh, \$mm, \$ss, \$ap) =
(\$1, \$2, \$3, \$4, \$5, \$6, \$7);
\$yy += 2000; \$mo = \$month{uc(\$mo)};
if (uc(\$ap) eq 'P' && \$hh != 12) {
\$hh += 12;
}
elsif (uc(\$ap) eq 'A' && \$hh == 12) {
\$hh -= 12;
}
return timelocal(\$ss, \$mm, \$hh, \$dd, \$mo, \$yy);
}
else { return 0; }
}

, Oct 30, 2007
8. ### TonyVGuest

On Oct 30, 5:42 pm, ""
<> wrote:
> Oops, actually this is the working version:

Great catch, I usually deal exclusively with 24-hour time, which is
why I probably introduced that bug in. I wish we could get rid of
that pesky AM/PM format entirely, even from our everyday, normal
lives.

TonyV, Oct 30, 2007
9. ### Guest

On Oct 30, 11:47 am, Paul Lalli <> wrote:
> \$date =~ s/\./:/ for 1..2;

That's a nifty little idiom that I would not have thought of (I would
have probably constructed some ugly regexp). I'm gonna write that
down on my Perl cheat-sheet!

--
The best way to get a good answer is to ask a good question.
David Filmer (http://DavidFilmer.com)

, Oct 31, 2007
10. ### Guest

On Oct 30, 1:47 pm, Paul Lalli <> wrote:
>
> #!/usr/bin/perl
> use strict;
> use warnings;
> use Date:arse 'str2time';
> my \$date = "22-OCT-07 06.16.44.160000 PM";
> \$date =~ s/\./:/ for 1..2;
> my \$epoch = str2time(\$date);
> print "Epoch: \$epoch\n";
> __END__

The Date:arse module looks great, but I can't seem to find it in
my ActiveState distribution of Perl, nor am I successful in installing
it with the command "ppm install Date-Parse".

Is there any one out there who is running ActiveState Perl and has
it, or am I the only one who's missing the Date:arse module? In
case anyone wonders, my "perl -v" output is:

This is perl, v5.8.8 built for MSWin32-x86-multi-thread
(with 33 registered patches, see perl -V for more detail)

Binary build 819 [267479] provided by ActiveState http://www.ActiveState.com
Built Aug 29 2006 12:42:41

Thanks.

, Oct 31, 2007
11. ### Guest

On Oct 31, 12:10 pm, "" <>
wrote:
>
> The Date:arse module looks great, but I can't seem to find it in
> my ActiveState distribution of Perl, nor am I successful in installing
> it with the command "ppm install Date-Parse".

Update: I was able to install the Date:arse module for
ActiveState Perl with the "cpan -i Date:arse" command. It required
the "nmake.exe" executable (and possibly others as well) to be in my
%PATH%, though.

, Oct 31, 2007
12. ### Ben MorrowGuest

Quoth "" <>:
> On Oct 30, 1:47 pm, Paul Lalli <> wrote:
> >
> > #!/usr/bin/perl
> > use strict;
> > use warnings;
> > use Date:arse 'str2time';
> > my \$date = "22-OCT-07 06.16.44.160000 PM";
> > \$date =~ s/\./:/ for 1..2;
> > my \$epoch = str2time(\$date);
> > print "Epoch: \$epoch\n";
> > __END__

>
>
> The Date:arse module looks great, but I can't seem to find it in
> my ActiveState distribution of Perl, nor am I successful in installing
> it with the command "ppm install Date-Parse".

Rather confusingly, ppm installs 'distributions' rather than 'modules',
and unlike CPAN.pm won't cross-reference them for you. If you look
Date:arse up on search.cpan.org you will see it is in the TimeDate
distribution, so you should be able to get it with

ppm install TimeDate

Ben

Ben Morrow, Nov 1, 2007
13. ### Guest

On Nov 1, 7:09 am, Ben Morrow <> wrote:
>
> Rather confusingly, ppm installs 'distributions' rather than 'modules',
> and unlike CPAN.pm won't cross-reference them for you. If you look
> Date:arse up on search.cpan.org you will see it is in the TimeDate
> distribution, so you should be able to get it with
>
> ppm install TimeDate

Thank-you for sharing that, Ben. I never knew that, and now I know
what to do in case I have trouble with it in the future.

(Oh, the "ppm install TimeDate" command you gave me worked
perfectly.)

Thanks again.

-- Jean-Luc Romano

, Nov 1, 2007