perl -MDate::Manip -le 'print "Last day" if UnixDate (ParseDate ($ARGV
+ [0]), "%B") ne UnixDate DateCalc ($ARGV [0], "1day"), "%B"' YYYYMMDD
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Sadly working on a windows server, weep weep.

Yes, and? Date::Manip is written in 100% Perl.

Abigail

The way I usually go about determining the last day of a month is:

use Time::Local;

### this will get me the Unix time
### for the last day in May

# get today's month and year
my ($m, $y) = (localtime)[4,5];

# get next month's month and year
my ($nm, $ny) = ($m == 11) ? (0, $y+1) : ($m+1, $y);

# get noon on the first of next month
my $next_month_noon = timelocal(0,0,12, 1,$nm,$ny);

# subtract a day from it (86400 seconds)
my $month_last_day = $next_month_noon - 86400;
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# my code above, as a function
sub lastday_time {
  use Time::Local;  # I never do this in real code
                    # I put module uses at the top of
                    # the entire program, not each sub

  # arguments are assumed to be in "human" terms
  my ($m, $y) = @_;
  $m--, $y -= 1900;  # perl-ify them

  my ($nm, $ny) = ($m == 11) ? (0,$y+1) : ($m+1,$y);

  # return the first of next month, minus one day
  return timelocal(0,0,12, 1,$nm,$ny) - 86400;
}


sub is_last_of_month {
  # arguments are "human"
  # lastday_time() subtracts 1 from $m and 1900 from $y

  my ($d, $m, $y) = @_;
  my $last_day = (localtime lastday_time($m,$y))[3];
  # fixed that last line -- I had $d, meant $m

  return $d == $last_day;
}
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perl -l -MDate::Calc=Days_in_Month -e 'print Days_in_Month(@ARGV)' 2004 2

my ($y, $m, $d) = unpack('A4A2A2', $ARGV[0]);
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I'd like to if I understood what is happening here.

unpack extracts values of various types from a string based on a format, in this case A4A2A2, and returns them as a list.
A is a space padded sting of bytes, the number after it is the number of bytes in each value.
So this format will return a string of the first 4 bytes (stripping away any trailing spaces if there were any) then the next 2 bytes and then the next 2 bytes.
The end result is identical to the 3 calls to substr, but a bit more concise.

$ARGV[ 0 ] =~ m[^(\d{4})(\d{2})(\d{2})] or die "Bad date: $ARGV[ 0 ]";
print "$ARGV[0] is NOT a month end day" 
    if $3-28-substr(' 303232332323',$2,1)-($2==2and not$1%4xor$1%100xo
+r$1%400);
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Very, Very good 2 months ago I would have sratched and gone back to bed but at least I know what I'm looking at now. Thanks.

use Time::Local;
print "last day" if (((localtime(time()+60*60*24))[3]) < 2);
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Just a bit of fun.

use Time::Local;

sub is_last_day_of_month
{
    my($y,$m,$d) = $_[0] =~ /(.{2,4})(..)(..)/;
    (gmtime(timegm(0,0,12,$d,$m-1,$y)+24*60*60))[4] != $m-1
}

my $a = shift;
print is_last_day_of_month($a)
    ? "$a: is last day of month\n"
    : "$a: is NOT last day of month\n";
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"I think you're taking a risk by trying to implement your own leap-year calculation."

Why? It's a simple and well documented algorithm, you can write it in a line of Perl. What's the risk?

Personally I keep hoping that a rudimentary date time module (maybe DateTime.pm or a subset) will be included with Perl core, then using the "comes with" will be easier than cutting and pasting the line of perl around :)

--
Do not seek to follow in the footsteps of the wise. Seek what they sought. -Basho

Still not sure why you'd want to. Just doing the leap-year check by hand is longer than some of the entire solutions presented.

And also:

use Time::Local;
sub is_leapyear {
  1 == (gmtime(timegm(0,0,1,28,1,$_[0])+24*60*60))[4]
}
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(But this has severe limitations on the range of valid dates input.)

The code thats gone into production uses something very similer to your example here. I'm only a contractor here and the full time staff(at the moment not perl experts) have to be able to maintain the code after I've gone, so the shortest version in this case is not the best. I just wonted to give myself a bit of a test and see where my skills where compared to the rest of the Monks. Still pretty low I'm afriad.

my ($y,$m,$d) = unpack "A4A2A2", $ARGV[0]; # ven'tatsu!
$d == 30+($m&1^$m>7)-($m==2)*(2-!($y%4||(!($y%100)&&$y%400)))
  or print "not month end day\n";
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perl -MTime::Piece -le'$t=localtime->strptime(shift,"%Y%m%d");print "l
+ast day" if $t->mday == $t->month_last_day' 20010731
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perl -MTime::Piece -le"$t=localtime->strptime(shift,'%Y%m%d');print 'l
+ast day' if $t->mday == $t->month_last_day" 20010731
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

While most, if not all of the nodes already giving feedback to your question have very good ideas, Abigail-II is on the money in my book. Date::Manip is probably the best date manipulation (as the name implies) module that I have come accross. It is a little large, but it works VERY well. It handles almost any form of manipulate, also uses regular speech paterns to decipher what you want to do (such as "last day of the month"). Also, the documentation is NOT lacking. This module will not only make your code shorter (as in the number of lines to produce the same result), it also makes your code a lot easier for someone else to read. It will definitly make life a lot easier where dates are concerned.