[28065] in Perl-Users-Digest
Perl-Users Digest, Issue: 9429 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Thu Jul 6 14:06:00 2006
Date: Thu, 6 Jul 2006 11:05:08 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Thu, 6 Jul 2006 Volume: 10 Number: 9429
Today's topics:
Re: date format <bart@nijlen.com>
Re: date format <someone@example.com>
Get the reference to an array from a function... <howachen@gmail.com>
Re: Get the reference to an array from a function... <aukjan@gmail.com>
Re: Get the reference to an array from a function... <aukjan@gmail.com>
Re: Get the reference to an array from a function... <howachen@gmail.com>
Re: Get the reference to an array from a function... <someone@example.com>
Re: Get the reference to an array from a function... <howachen@gmail.com>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: 6 Jul 2006 01:01:12 -0700
From: "Bart Van der Donck" <bart@nijlen.com>
Subject: Re: date format
Message-Id: <1152172868.858828.53950@b68g2000cwa.googlegroups.com>
John W. Krahn wrote:
> [...]
> A lot of date formats use a leading space for single digit days so splitting
> on a single space character will give you an off-by-one error on the day and
> year fields.
Yes, I think I remember there was something tricky with it, that's why
I did sprintf('%02g',$ar[4]); in stead of just print $ar[4] in my
program. Thanks for pointing that out, the solution is simple:
my @ar = split / +/, (split /\n/, $file)[0];
>> $ar[3] =~ s/$m[$_]/@{[sprintf('%02g',$_+1)]}/ for (0..$#m);
>
> Is there a good reason to use a floating-point format ('g') instead of an
> integer format ('i', 'd' or 'u')?
Well, it's there to guarantee the two-digit MM (month) format. I don't
see any drawbacks for that here, but maybe I'm not fully aware of the
exact finetunings of this construction.
>> die "Can't find month '$ar[3]'\n" unless $ar[3]=~/^(0|1)[0-9]$/;
>
> Why use an alternation with capturing parentheses instead of a character
> class? Where do you use the value stored in $1? So you are saying that 19 is
> a valid month?
You're right, something like
die "..." unless $ar[3]=~ /^0[1-9]$|^1[0-2]$/;
should do.
Thanks for your comment. I learnt from it.
--
Bart
------------------------------
Date: Thu, 06 Jul 2006 11:46:54 GMT
From: "John W. Krahn" <someone@example.com>
Subject: Re: date format
Message-Id: <OK6rg.104745$A8.91205@clgrps12>
Bart Van der Donck wrote:
> John W. Krahn wrote:
>
>>>$ar[3] =~ s/$m[$_]/@{[sprintf('%02g',$_+1)]}/ for (0..$#m);
>>Is there a good reason to use a floating-point format ('g') instead of an
>>integer format ('i', 'd' or 'u')?
>
> Well, it's there to guarantee the two-digit MM (month) format. I don't
> see any drawbacks for that here, but maybe I'm not fully aware of the
> exact finetunings of this construction.
The array index (0..$#m) will always be an integer. The underlying C library
uses type promotion so the integer will be converted to a double
floating-point number in order to convert it to a string. If the integer is
large enough it will be converted using scientific notation:
$ perl -le'print for $^T, sprintf( q[%02g], $^T ), sprintf q[%02d], $^T'
1152186353
1.15219e+09
1152186353
John
--
use Perl;
program
fulfillment
------------------------------
Date: 6 Jul 2006 01:45:51 -0700
From: "howa" <howachen@gmail.com>
Subject: Get the reference to an array from a function...
Message-Id: <1152175551.395194.49440@m73g2000cwd.googlegroups.com>
hi,
consider the program, why reference to an array returning from a
function did not work?
#------------------------------
sub test {
my @arr = ("1", "2", "3");
return @arr;
}
my $size = test();
my @arr = test();
my $arr_ref = \test();
use Data::Dumper;
#print Dumper ( $size );
#print Dumper ( @arr );
print Dumper ( $arr_ref ); # DIDN'T WORK!
------------------------------
Date: Thu, 06 Jul 2006 11:02:21 +0200
From: Aukjan van Belkum <aukjan@gmail.com>
Subject: Re: Get the reference to an array from a function...
Message-Id: <b5fc9$44acd17a$c2abfc64$28381@news2.tudelft.nl>
howa wrote:
> hi,
>
> consider the program, why reference to an array returning from a
> function did not work?
>
>
> my $arr_ref = \test();
You should change this line to:
my $arr_ref = [ test() ];
This will force a list of values returned by test into an array
reference. Using \test() will actually do nothing, and if you would
have written it as:
my $arr_ref = \&test();
You would have created a reference to the subroutine 'test';
Aukjan
------------------------------
Date: Thu, 06 Jul 2006 11:06:16 +0200
From: Aukjan van Belkum <aukjan@gmail.com>
Subject: Re: Get the reference to an array from a function...
Message-Id: <5fd39$44acd265$c2abfc64$28381@news2.tudelft.nl>
Aukjan van Belkum wrote:
> Using \test() will actually do nothing,
To correct myself... "my $ref = \test()" will actually return a
reference to the last returned value in the list.
check: "perldoc perlref" for more info
Aukjan
------------------------------
Date: 6 Jul 2006 03:09:01 -0700
From: "howa" <howachen@gmail.com>
Subject: Re: Get the reference to an array from a function...
Message-Id: <1152180541.658751.77920@75g2000cwc.googlegroups.com>
Aukjan van Belkum =E5=AF=AB=E9=81=93=EF=BC=9A
> howa wrote:
> > hi,
> >
> > consider the program, why reference to an array returning from a
> > function did not work?
> >
> >
> > my $arr_ref =3D \test();
>
> You should change this line to:
>
> my $arr_ref =3D [ test() ];
>
> This will force a list of values returned by test into an array
> reference. Using \test() will actually do nothing, and if you would
> have written it as:
>
> my $arr_ref =3D \&test();
>
> You would have created a reference to the subroutine 'test';
>=20
> Aukjan
Thanks!
------------------------------
Date: Thu, 06 Jul 2006 11:16:25 GMT
From: "John W. Krahn" <someone@example.com>
Subject: Re: Get the reference to an array from a function...
Message-Id: <di6rg.104740$A8.5373@clgrps12>
Aukjan van Belkum wrote:
> Aukjan van Belkum wrote:
>> Using \test() will actually do nothing,
>
> To correct myself... "my $ref = \test()" will actually return a
> reference to the last returned value in the list.
test() returns a list and \test() will return a list of references to the
items in the original list. Only the last item will be stored in the scalar
because that is the way that scalar assignment works with a list.
John
--
use Perl;
program
fulfillment
------------------------------
Date: 6 Jul 2006 09:41:42 -0700
From: "howa" <howachen@gmail.com>
Subject: Re: Get the reference to an array from a function...
Message-Id: <1152204100.609651.295610@j8g2000cwa.googlegroups.com>
John W. Krahn =E5=AF=AB=E9=81=93=EF=BC=9A
> Aukjan van Belkum wrote:
> > Aukjan van Belkum wrote:
> >> Using \test() will actually do nothing,
> >
> > To correct myself... "my $ref =3D \test()" will actually return a
> > reference to the last returned value in the list.
>
> test() returns a list and \test() will return a list of references to the
> items in the original list. Only the last item will be stored in the sca=
lar
> because that is the way that scalar assignment works with a list.
>
in fact, what does "\test()" means as it is not the reference to the
list returning from the function?
>>\test() will return a list of references to the items in the original lis=
t=2E
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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End of Perl-Users Digest V10 Issue 9429
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