simple question

pietyc has asked for the wisdom of the Perl Monks concerning the following question:

Hello
I am a very new to PERL. When I run the program why is it that $new_date is printed on three lines rather than one? Below is the output I get from the code further below. Thank you for any help.

-Charles

the year is 2004
the month is 03
the day is 04
2004
03
04
2004
03
03

#!/usr/bin/perl
my $yr = `date -u +%Y`; #get the output of year
my $mm = `date -u +%m`; #get the output of month
my $dd = `date -u +%d`; #get the output of day
my $yyyymmdd = `date -u +%Y%m%d`;

print "the year is $yr";
print "the month is $mm";
print "the day is $dd";

$new_date = "$yr$mm$dd";

print $new_date;

$yes_dd = $dd -1;

$yes_dd = 0 . $yes_dd;

$yes_date = $yr.$mm.$yes_dd;

print "$yes_date\n";
[download]

Edit by dws to add <code> tags

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Re: simple question by tachyon (Chancellor) on Mar 04, 2004 at 23:27 UTC
No one has mentioned it but you don't typically shell out to date in perl. Perl has lots of date handling built in. See localtime gmtime and lots of other stuff like Date::Manip Date::Calc Time::Local `my $string_time = localtime(time()); my $yesterday = localtime(time()-246060); my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time); print "$string_time\n$yesterday\n"; printf "%02d:%02d:%02d %02d/%02d/%4d\n", $hour, $min, $sec, $mday, $mo +n+1, $year+1900;` [download] HTH cheers tachyon	[reply] [d/l]
Re: simple question by matija (Priest) on Mar 04, 2004 at 20:51 UTC
The output of the `date ...` contains the newline at the end. So when you print them, you print the newlines, too. You could `chomp` each variable separately, or you could chomp them all at once, like this: `chomp ($yr,$mm,$dd,$yyyymmdd);` [download]	[reply] [d/l] [select]
Re: simple question by onegative (Scribe) on Mar 04, 2004 at 20:47 UTC
use the chomp function to get rid of the new line characters that are hidden. `chomp($yr); chomp($mm); chomp($dd);` [download]	[reply] [d/l]
Re: simple question by esskar (Deacon) on Mar 04, 2004 at 20:50 UTC
date adds a "\n" at the end of its outout my $yr = `date -u +%Y`; #get the output of year my $mm = `date -u +%m`; #get the output of month my $dd = `date -u +%d`; #get the output of day chomp $yr; chomp $mm; chomp $dd; [download] hint: `perldoc -f localtime`	[reply] [d/l] [select]
Re: Re: simple question by Happy-the-monk (Canon) on Mar 04, 2004 at 21:46 UTC
just to second esskars hint: `perldoc -f localtime` will point you to a much smoother way of determining time and date.	[reply]
Re: simple question by BUU (Prior) on Mar 04, 2004 at 20:49 UTC
It prints on multiple lines becaue the data you get from `data -u etc` contains a new line at the end. That is why `print "the year is $yr"; print "the month is $mm";` [download] appears on different lines in the output, both $yr and $mm have a new line at the end. If you want to get rid of the new line, try chomp.	[reply] [d/l] [select]
Re: simple question by ambrus (Abbot) on Mar 04, 2004 at 20:50 UTC
This is because date prints a newline, and the backquotes catch it, so the newlines are in the string $yr and $mm. Date has to print a newline, as otherwise the output would get into the same line as your prompt if you call it from the shell (this is like this only on unix systems, dos prints a newline before the prompt). To correct it, remove the newlines from the strings with the command `chomp ($yr, $mm, $dd);` [download] Update: Five identical answers to the question, wow!	[reply] [d/l]
Re: simple question by bfdi533 (Friar) on Mar 04, 2004 at 22:28 UTC
The output from date is terminated by a newline and you have that in your string. You should use chomp to strip off the newline like this: $yr = `date -u +%Y`; chomp $yr; [download] Ed	[reply] [d/l]