Questions in: Cgi Perl

chop is used remove last character,chomp function removes
only line endings.

chop will indiscriminately remove (and return) the last
character passed to it, while chomp will only remove the
end of record marker (generally, "n"), and return the
number of characters so removed.

Hash is an associative array where data is stored in
"key"->"value" pairs.
Eg : fruits is a hash having their names and price
%fruits = ("Apple", "60", "Banana", "20", "Peers", "40");

As friends said above, its otherwise called as associative
array. It has lot of advantages over perl.
Here we can keep the values in a structured way, that
structured way comes from key-value pairs.
Eg: (The syntax given above are also correct, but the below
representation is much better in look and feel)
my %hash_example = ( a => 10,
b => 20,
c => 30 );
keys : a,b,c
values : 10,20,30
Features of Hash :
##################
1) Keys should always be unique where as values may not be
unique
(Right)
my %hash_example = ( a => 10,
b => 10,
c => 10 );
(wrong)
my %hash_example = ( a => 10,
a => 20,
a => 30 );
2) keys (%hash_example) will return an array containing only
keys
my @keys = keys(%hash);
3) similary for values
my @values = keys(%values);

1. When you are developing an application for a real time
system in which processing speed is of utmost importnace
When to use Perl
1. For large text processing
2. When application does lot of data manipulation
3. When you need fast development
4. For database loading operations
5. When shell scrits grow to become libraries

for and foreach works alike.
But for uses condition expression, where as foreach works on
ranges, contineous indexing.

for and foreach are alias of each other.But syntax is different.
e.g for(my $i = 0; $i < 3; ++$i){print $i}
e.g foreach my $i (0 .. 2){print $i}
i.e in foreach we can take always only array of elements or
range of elements.But in for we dont have to take the array
or range always.here we can provide condition of the loop
where it is not true for foreach.

You might have asked the question in reverse.For daily needs
and for normal development purposes in Perl, we need to use
many modules.
We will get the modules from a common repository called
"Cpan", in which programmers from all over the world keep
the modules. Anyone can use them.
Eg.,
Data::Dumper
CGI
HTML::Template
CGI::Carp qw(fatalsToBrowser);
CGI::Ajax ...
...........
..........

There are no.of instances for this
For eg; we use DBI module for database connectivity,
and we also use CGI Module for parsing the form input and
printing the headers.

open FILEHANDLE, ">$FILENAME"

Files are opened using the open and sysopen function.
Either function may be passed up to 4 arguments, the first
is always the file handle thenfile name also known as a URL
or filepath, flags, and finally any permissions to be
granted to this file.
$FH = "filehandle";
$FilePath = "myhtml.html";
open(FH, $FilePath, permissions);
or
sysopen(FH, $FileName, permission);

#!usr/bin/perl
use strict;
use warnings;
my $string="XmanXseriesx";
my $count = ($string =~ tr/X//);
print "There are $count Xs in the stringn";
print $string;

$str='Hello';
$cnt= ($str=~s/l/i/g);
print $cnt;
$cnt stores the number of replacements.

-w to enable warnings mode
-T to enable Taint mode (TAINT mode puts a Perl script
into "PARANOID" mode and treats ALL user supplied input as
tainted and bad unless the programmer explicitly "OKs" the
data). Usually used when you are using a perl script that
you have downloaded and running but do not want any
security problems.
strict is a pragma in perl used to incorporate strict
programming practices.
Eg:
you could have written a small prog like this:
$x=100;
print $x;
with strict pragma "ON" you will be explicitly required to
specify the scope like,
use strict;
my $x=100; ##use of my to specify scope
print $x;
You can also switch off a pragma by using "no" like below
to switch off the pragma effect:
use strict;
my $x=100; ##use of my to specify scope
print $x;
no strict;
$y=200; ##no need to be specific
print $y;

-w enables the warnings mode in perl
-T is enables the Taint mode it performs some checks how
your program is using the data passed to it
-w, -T,-d, -D are called the command line switches

use can take a bareword and require doesnot while accessing
module
use is used in compile time ie all code is parsed before
program run where as require is used in run time. So if
there is much code in initialization include that in use
rather than require
use supports import method by default and require doesnt
support
Inside use default import method will be present. BEGIN {
require Module; }

Use :
1. The method is used only for the modules(only to include
.pm type file)
2. The included objects are varified at the time of compilation.
3. No Need to give file extension.
Require:
1. The method is used for both libraries and modules.
2. The included objects are varified at the run time.
3. Need to give file Extension.

My Favorite module is LWP and WWW because it is used to connect the perl into the web and getting the source page.

My Favourite module is CGI.pm Bcoz it can handle almost all
the tasks like
1. parsing the form input
2. printiing the headers
3. can handle cookies and sessions
and much more

ip_pattern = r'b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?).){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)b'

(/(d{1,3}).(d{1,3}).(d{1,3}).(d{1,3})/ && $1 < 255 &&
$2 < 255 && $3 < 255 && $4 < 255 )

Perl is a general purpose, high level, interpreter, dynamic
and open souce programming language. It's a powerful text
processing software and also used in system administration,
web developement, network programming language etc. We can
use it in both linux/unix and Windows environment also.
Hope this should be enough to the reason for programming in
PERL.

It is having the features of scripting(shell) as well as
programming(like c). Using perl u can easily do the system
administration works where comparitively difficult with
shell script.

The variables declared with "my" can live only within the
block it was defined and cannot get its visibility
inherited functions called within that block, but one
defined with "local" can live within the block and have its
visibility in the functions called within that block.

You can consider "my" as local and "local" as global
variable like C,C++.
The scope of "my" lies between the block only but if we
declare one varable global then we can asccess that from
the outside of the block also.

"Use strict" is one of the pragma used for checking the
variable scope and syntax. If you use this pragma means,
you need to specify the scope (my, local, our) for the
variable and use the exact usage of operators.
For eg. Checking equality $number = 1 and $char eq 'a'.

strict is a pragma that can be used to enforce Strict
programming practices while you write your programs.
Eg: You can write a program like this:
$x=100
print $x
But if you use strict pragma, then you have to be very
specific while using variables
use strict;
my $x=100; ##look at the usage of scope like my,local,our
print $x;
Pragma usage can also be used as a toggle
use strict;
my $x=100;
print $x;
no strict; # to toggle strict to "No"
$y=200; ##no need to use scope as strict is disabled
print $y;

$ indicate scalar data type
@ indicates an array and
% indicates an hash or an associative array.

the element is keyword "sub"
means write the subroutines,
which allow maximum readability
and allow maximum-reuse
if want any other;
write the classes and package..

Here are my views
1.The Project should be an internal client but not mandatory
2.Minimal number of users can hit because of performance
issues
3.If the Project is dealing with many number of emails
sending
4.To develop faster and kick it off

Mainly we are using -w argument for perl interpreter. That
means you are turning on warning messages.

Hi The various command line arguments are -e executes the
prog given as an argument-d start perl debugger on the file
name specified as an argument-c compile the file given as an
argument

CGI is software programme through which a communication
take place between user rquest web and server.

The Common Gateway Interface is a standard for communication
between Web servers and external programs.

In the form Action you have to specify the (perl) program,
you want to execute on submitting this form.

In the HTML form, you have to mention the perl script name.
Ex: <form action="test.pl" method="POST">. Then in the
test.pl, you have to mention the content-type as
print "content-type: text/htmlnn";. And read the form
values and print them.