perl::critic::policy::variables::requirenegativeindices(3) [centos man page]
Perl::Critic::Policy::Variables::RequireNegativeIndices(User Contributed Perl DocumentatPerl::Critic::Policy::Variables::RequireNegativeIndices(3)NAME
Perl::Critic::Policy::Variables::RequireNegativeIndices - Negative array index should be used.
AFFILIATION
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION
Perl treats a negative array subscript as an offset from the end. Given this, the preferred way to get the last element is $x[-1], not
$x[$#x] or $x[@x-1], and the preferred way to get the next-to-last is $x[-2], not "$x[$#x-1" or $x[@x-2].
The biggest argument against the non-preferred forms is that their semantics change when the computed index becomes negative. If @x
contains at least two elements, $x[$#x-1] and $x[@x-2] are equivalent to $x[-2]. But if it contains a single element, $x[$#x-1] and
$x[@x-2] are both equivalent to $x[-1]. Simply put, the preferred form is more likely to do what you actually want.
As Conway points out, the preferred forms also perform better, are more readable, and are easier to maintain.
This policy notices all of the simple forms of the above problem, but does not recognize any of these more complex examples:
$some->[$data_structure]->[$#{$some->[$data_structure]} -1];
my $ref = @arr; $ref->[$#arr];
CONFIGURATION
This Policy is not configurable except for the standard options.
AUTHOR
Chris Dolan <cdolan@cpan.org>
COPYRIGHT
Copyright (c) 2006-2011 Chris Dolan.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
perl v5.16.3 2014-06-09 Perl::Critic::Policy::Variables::RequireNegativeIndices(3)
Check Out this Related Man Page
Perl::Critic::Policy::Variables::ProhibitMatchVars(3) User Contributed Perl Documentation Perl::Critic::Policy::Variables::ProhibitMatchVars(3)NAME
Perl::Critic::Policy::Variables::ProhibitMatchVars - Avoid "$`", "$&", "$'" and their English equivalents.
AFFILIATION
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION
Using the "match variables" "$`", $&, and/or "$'" can significantly degrade the performance of a program. This policy forbids using them
or their English equivalents. See perldoc English or PBP page 82 for more information.
It used to forbid plain "use English;" because it ends up causing the performance side-effects of the match variables. However, the
message emitted for that situation was not at all clear and there is now Perl::Critic::Policy::Modules::RequireNoMatchVarsWithUseEnglish,
which addresses this situation directly.
CONFIGURATION
This Policy is not configurable except for the standard options.
AUTHOR
Chris Dolan <cdolan@cpan.org>
COPYRIGHT
Copyright (c) 2006-2011 Chris Dolan.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license
can be found in the LICENSE file included with this module.
perl v5.16.3 2014-06-09 Perl::Critic::Policy::Variables::ProhibitMatchVars(3)
i need to seperate values seperated by delimiters and assign it to an array.. can u plz help me on that.
Variables = "asd,rgbh,(,rty,got,),sroe,9034,"
i need to assign the variables into arrays..
like..
var=asd
var=rgbh.. and so on
how do i do this. i need to reuse the values stored in... (6 Replies)
Hi.
I have three arrays.
@a=('AB','CD','EF');
@b=('AB,'DG',HK');
@c=('DD','TT','MM');
I want to compare the elements of the first two array and if they match then so some substition.
I tried using the if statement using the scalar value of the array but its not giving me any output.
... (7 Replies)
Hi All,
I can;t seem to print out the array in sequence using the below subroutine.
My first element in the array @lotsuffix is suppose to be $lotsuffix as defined in the subroutine, but when the array variable is being pass on the main program, my first element actually becomes $lotsuffix ! ... (4 Replies)
I'm currently working with dozens of FASTA files, and I'm tired of having to manually change the filename in my Perl script.
I'm trying to write a simple Perl script that'll create a 2-dimensional array containing the name of the folders and its contents.
For example, I would like the output... (6 Replies)
#!/usr/bin/perl
my @arr=("hello", "how", "are", "you");
$l=length(@arr);
print $l;
This print 1.Why?
How can i print the array size = 4?
I want to store these in an array.
hello
how
are
you
And then i want to access these element through indexing.
How can i do this? (4 Replies)
Hello Everyone,
I've googled everywhere for this with no luck and my brain hurts.
I'm trying to write a program to take my webpages and search for forms.
I've used LWP::Simple to store a website in $content
I need to cut the form out of $content. I don't know how to do this seeing as how... (2 Replies)
I need to calculate the biggest number in array size n.
Example: Users enter: 1 7 4 9
The biggest number is : 9
Simple but I'm really new on this on Shell/Bash! Anything will be helpful! Thanks!
#!/bin/bash
printf "\tEnter a list of numbers, with spaces: "
read -a ARRAY
BIG=$1... (5 Replies)
First time poster here and I'm pretty much a total noob with UNIX and Perl. So please bear with me.
With Perl, I'm trying to fill an array with data that is in a CSV file. I would like to fill the array with only one of the columns in the CSV file.
I have a file called data.csv:
... (2 Replies)
Hi All,
I am new to perl I am stuck in simple problem I need your help
I want to define a subroutine.
sub check_if_entity_exists(@array_to_be_checked,$entityName)
I have array as
http-listener-1
http-listener-2
http-listener-3
http-listener-4
If i send http-listener-3 my... (1 Reply)
Ive been trying to move to Perl. It has been a struggle.
My question is, is there a good resource that explains nesting statements.
As an example.
To change
primary
Factory CTS 1.9.0(46) P1
*Slot 1 CTS 1.10.2(42) P1
To
primary *Slot 1 CTS 1.10.2(42) P1
... (5 Replies)