On Thu, Oct 15, 2009 at 2:55 PM, Raheel Hassan <raheel.has...@gmail.com>wrote:
> Hi,
>
> I will be very thankful if someone explains under given code.
>
> #----- CGI Module ------------------------------
> use CGI;
>
> $q = CGI->new();
>
> my ($myself) = split(/\?/,$q->self_url); #from where it will call the
> url?
> my @base_url = split(/\//, $myself); #what is \ /
> my $base_url = $base_url[0]."//".$base_url[2]."/";
> my $validate_url = $q->self_url."&validate=1";
> my $id = $q->param("id"); #what is the role
> of param here?
> my $hub = $q->param("HUB");
>
> Regards,
> Raheel.
>
Lets have a go at this then :-)
my ($myself) = split(/\?/,$q->self_url); #from where it will call
the url?
my @base_url = split(/\//, $myself); #what is \ /
my $id = $q->param("id"); #what is the
role of param here?
To understand the first line you have to understand what the line before
that does...
$q = CGI->new();
This creates a new CGI object. As most objects a CGI object has various
attributes one of them being the URL used to start the CGI script. So
$q->self_url returns the value of this attribute.
The next line is a lot easier: in a regular expression or a split where you
use the default delimiters for the expression / and / means you cannot just
tell perl to split on / as that would for perl indicate the end of the
expression. So you escape the / part of the expression with a \ resulting in
the following /\// meaning split the string on the character /.
As we determined before $q contains a CGI object this object has attributes
one of them is the URL used to start the script another one is a hash with
parameters found behind the URL. Think of a URL like this:
http://mysite.com/cgi-bin/script.cgi?id=1&start=hello
The attribute self_url in this case is: mysite.com/cgi-bin/script.cgi
The parameters are: start with the value hello and id with the value 1
*(Note, you might want to have a look at the difference between GET and POST
variables. In the HTML 4.1 specification as understanding the difference can
save you a lot of trouble when working with CGI)*
Figuring out what these parameters are is done by calling CGI
Object->param("<parameter name>").
Since the script stored the CGI Object in the variable $q making the
following call $q->param("id") will return the value of the parameter with
the name: id.
Hope that helped a bit.
Rob
