Your syntax is fine: You're creating an array called @var, indexed from 0 to 2, and printing the middle element. To do this from the command line:
Since you got the manpages, read "perlrun" for details on the "-e" switch and other nifty stuff you can do. There are more comments to make, but since you're just getting started, do what it says in the main perl manpage and read the first 5 or 6 in the order given.
Hi
Is there any way to use UNIX and Perl to automate sending e-mail. I got a dynamic changing file that send out to people in my mailing list and want to experinment to see if Perl and UNIX can send it out for me when the content is change. I found a Perl source code but dont really know how to... (4 Replies)
Does anyone know how I can add a variable to a one line perl command such as the following:
#! /bin/bash
date=`date +%Y%m%d`
perl -i -pe 's/(1\.1\.0\.).+/${1}${date}/' ./build_date
I'd like the ${date} variable to be evaluated by the perl command. So that the perl command will read each... (2 Replies)
Hi,
My perl script takes few switches which i'm parsing through GetOpt::Long module.
My script looks like something :
myscript.pl --file="foo" --or --file="bar"
The --file switch takes 2 arguments foo and bar.
The 2 values of file are separated by --or switch. I want to ensure that... (1 Reply)
I had posted previously about this problem I had.
I have multiple text files with hundreds of lines of the following type:
2000001 34 54 234 2000001
32 545 2000001 -2000001 77 2000001 44 2000001 998 2000001
77 32 2000001 45 23 111 89
98 75 23 34 999
.
.
.
etc...
What I wanted was... (2 Replies)
Hi all,
I want to get options from command line by perl.
usage()
options:
-h Show this help message and exit
-t Name of tester
--timeout Set the timeout
-l ... (1 Reply)
Hi,
I use find command to list all the files in a directory and its sub-directories, but the problem is to exclude certain directories during search. Can i give the directory names in command line to skip them and search rest of the directories?
For example i have directories:
test
../test1... (1 Reply)
so in unix this command works works and shows me a list of directories
find . -name \*.xls -exec dirname {} \; | sort -u | > list.txt
but when i try running a perl script to run this command
my $query = 'find . -name \*.xls -exec dirname {} \; | sort -u | > list.txt';... (2 Replies)
how do i check if a command line argument is -g?
for example,
if command line argument equals "-g"
{
print "Goodbye \n";
}
else
{
print "Welcome to the program! \n";
} (1 Reply)
Hi
I need to write a Perl script that the file given as first argument of the command line that will find all occurrences of the string given as the third argument of the command line and replace with the string given as the fourth argument. Name newfound file is specified as the second... (3 Replies)
I am looking for help in processing of those options: '-n' or '-p'
I understand what they do and how to use them.
But, I would like to use them with more than one file (and without any shell-loop; loading the 'perl' once.)
I did try it and -n works on 2 files.
Question is:
- is it possible to... (6 Replies)
Discussion started by: alex_5161
6 Replies
LEARN ABOUT DEBIAN
devel::refcount
Devel::Refcount(3pm) User Contributed Perl Documentation Devel::Refcount(3pm)NAME
"Devel::Refcount" - obtain the REFCNT value of a referent
SYNOPSIS
use Devel::Refcount qw( refcount );
my $anon = [];
print "Anon ARRAY $anon has " . refcount($anon) . " reference
";
my $otherref = $anon;
print "Anon ARRAY $anon now has " . refcount($anon) . " references
";
DESCRIPTION
This module provides a single function which obtains the reference count of the object being pointed to by the passed reference value.
FUNCTIONS
$count = refcount($ref)
Returns the reference count of the object being pointed to by $ref.
COMPARISON WITH SvREFCNT
This function differs from "Devel::Peek::SvREFCNT" in that SvREFCNT() gives the reference count of the SV object itself that it is passed,
whereas refcount() gives the count of the object being pointed to. This allows it to give the count of any referent (i.e. ARRAY, HASH,
CODE, GLOB and Regexp types) as well.
Consider the following example program:
use Devel::Peek qw( SvREFCNT );
use Devel::Refcount qw( refcount );
sub printcount
{
my $name = shift;
printf "%30s has SvREFCNT=%d, refcount=%d
",
$name, SvREFCNT($_[0]), refcount($_[0]);
}
my $var = [];
printcount 'Initially, $var', $var;
my $othervar = $var;
printcount 'Before CODE ref, $var', $var;
printcount '$othervar', $othervar;
my $code = sub { undef $var };
printcount 'After CODE ref, $var', $var;
printcount '$othervar', $othervar;
This produces the output
Initially, $var has SvREFCNT=1, refcount=1
Before CODE ref, $var has SvREFCNT=1, refcount=2
$othervar has SvREFCNT=1, refcount=2
After CODE ref, $var has SvREFCNT=2, refcount=2
$othervar has SvREFCNT=1, refcount=2
Here, we see that SvREFCNT() counts the number of references to the SV object passed in as the scalar value - the $var or $othervar
respectively, whereas refcount() counts the number of reference values that point to the referent object - the anonymous ARRAY in this
case.
Before the CODE reference is constructed, both $var and $othervar have SvREFCNT() of 1, as they exist only in the current lexical pad. The
anonymous ARRAY has a refcount() of 2, because both $var and $othervar store a reference to it.
After the CODE reference is constructed, the $var variable now has an SvREFCNT() of 2, because it also appears in the lexical pad for the
new anonymous CODE block.
PURE-PERL FALLBACK
An XS implementation of this function is provided, and is used by default. If the XS library cannot be loaded, a fallback implementation in
pure perl using the "B" module is used instead. This will behave identically, but is much slower.
Rate pp xs
pp 225985/s -- -66%
xs 669570/s 196% --
SEE ALSO
o Test::Refcount - assert reference counts on objects
AUTHOR
Paul Evans <leonerd@leonerd.org.uk>
perl v5.14.2 2011-11-15 Devel::Refcount(3pm)