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Posting to comp.lang.perl.misc
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This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

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4.38: Why don't my <
Check for these three things:

There must be no space after the << part.
There (probably) should be a semicolon at the end.
You can't (easily) have any space in front of the tag.

If you want to indent the text in the here document, you can do this:

# all in one
($VAR = < your text
goes here
HERE_TARGET

But the HERE_TARGET must still be flush against the margin. If you want
that indented also, you'll have to quote in the indentation.

When I run the following...

#!/usr/bin/perl -w

open (PRODUCT,"C:\Documents and Settings\root\Desktop\wd\hp.mhtml") ||
die "Cant open: $!;

I get the following

Unrecognized escape \D passed through at ./parse.pl line 3.
Unrecognized escape \D passed through at ./parse.pl line 3.
Unrecognized escape \w passed through at ./parse.pl line 3.
Unrecognized escape \h passed through at ./parse.pl line 3.
Can't find string terminator '"' anywhere before EOF at ./parse.pl
line 3.

What escape characters is Windows complaining about and how do I fix
them?

Chad

Hello,

a CPAN module of mine that needs a C compiler for installation
fails in some of the tests since the C compiler isn't found. The
offending lines are

if ( system $Config{cc}, qw( -o cc_test cc_test.c ) ) {
unlink 'cc_test.c';
die "Can't run C compiler '$Config{cc}'\n";
}

where 'cc_test.c' is a simple program that gets created
automatically just for this test.

The problem is that on one of the testers machines $Config{cc}
is set to 'ccache cc' and system() obviously does not like the
space in the name of the program it's supposed to execute.

Now I probably can get around that by using a line like

if ( system split /\s+/, $Config{cc}, qw( -o cc_test cc_test.c ) ) {

This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

--------------------------------------------------------------------

4.47: How do I handle circular lists?

Circular lists could be handled in the traditional fashion with linked
lists, or you could just do something like this with an array:

unshift(@array, pop(@array)); # the last shall be first
push(@array, shift(@array)); # and vice versa

You can also use "Tie::Cycle":

use Tie::Cycle;

tie my $cycle, 'Tie::Cycle', [ qw( FFFFFF 000000 FFFF00 ) ];

print $cycle; # FFFFFF
print $cycle; # 000000
print $cycle; # FFFF00

--------------------------------------------------------------------

Hi, I've currently got a laptop running Ubuntu Server and Perl 5.8.8.
I've installed the Device::ParallelPort module and I have it working
fairly reliably with ouput. I can make it turn on an LED on some
breadboard, etc.

I am having problems with receiving input through the parallel port
though. I really need to react to something happening. I currently
have pin 12 (Paper-Out/Paper-End) connected to +5V through a switch.
When I press the switch the bit should be set.

Unfortunately I don't actually seem to get what I'm looking for at
all. I'm having no end of trouble finding any example code using this
module for anything but regular 8-pin output.

Has anyone got any tips, bookmarks, or information at all about using
this module for receiving input on the status pins?

Any help would be greatly appreciated.

Regards,
Stuart.

This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

--------------------------------------------------------------------

4.32: How do I strip blank space from the beginning/end of a string?

(contributed by brian d foy)

A substitution can do this for you. For a single line, you want to
replace all the leading or trailing whitespace with nothing. You can do
that with a pair of substitutions.

s/^\s+//;
s/\s+$//;

You can also write that as a single substitution, although it turns out
the combined statement is slower than the separate ones. That might not
matter to you, though.

s/^\s+|\s+$//g;

I need to get the current date-time with milliseconds upto 5 places of
precision.

That is, 20080512T12094565266 => YYYY MM DD T HH mm SS ms-5 digits

Here, 65266 is the milli-second with 5 places of precision.

I tried with the module DateTime, but that does not give the
milliseconds.

use DateTime;
my $dt = DateTime->now( time_zone => 'floating' );

Any idea how this can be achieved in Perl?

Thanks.

This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

--------------------------------------------------------------------

4.14: How can I compare two dates and find the difference?

(contributed by brian d foy)

You could just store all your dates as a number and then subtract. Life
isn't always that simple though. If you want to work with formatted
dates, the "Date::Manip", "Date::Calc", or "DateTime" modules can help
you.

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