Perl Formula Help - Changing a Price in script
Hello - I am new to Perl, and looking for some much needed direction.
I am trying to get a basic formula in place (within an existing IF
statement) that will serve to increase my price (i.e., $new_price)
by the following formula:
=PRICE divided by 0.8 plus 15
In other words, if the Price is equal to 3, the results of the
$new_price should be 18.75. And if the price is equal to 5, then the
$new_price should be equal to 21.25.
The script that I am trying to alter is shown below. Can someone
possibly let me know how I can alter the below script (which I believe
would mean to alter the line that reads $new_price = $o_list[2]-
{price};) so that the new price would would work as described above?
Also, just a layman's explanation of the syntax shown below would be
greatly helpful. I am trying to understand what the -= and the -
and the ? characters represent.
Thanks for any suggestions or guidance.
#
if ( @o_list ) {
if ( defined ( $o_list[2] ) ) {
$new_price = $o_list[2]-{price};
$new_price -= $new_price = 0 ? $new_price - .01 : 0;
}
}
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Re: Perl Formula Help - Changing a Price in script
Dave K wrote:
Hello - I am new to Perl, and looking for some much needed direction.
I am trying to get a basic formula in place (within an existing IF
statement) that will serve to increase my price (i.e., $new_price)
by the following formula:
=PRICE divided by 0.8 plus 15
In other words, if the Price is equal to 3, the results of the
$new_price should be 18.75. And if the price is equal to 5, then the
$new_price should be equal to 21.25.
The script that I am trying to alter is shown below. Can someone
possibly let me know how I can alter the below script (which I believe
would mean to alter the line that reads $new_price = $o_list[2]-
{price};) so that the new price would would work as described above?
Also, just a layman's explanation of the syntax shown below would be
greatly helpful. I am trying to understand what the -=
$x -= $y;
Is short for:
$x = $x - $y;
It is borrowed from the C programming language.
and the -
That is the dereference operator.
perldoc perlop
perldoc perlref
perldoc perldsc
and the ? characters represent.
? : is the conditional operator.
my $x = $a $b ? $y : $z;
Is equivalent to:
my $x;
if ( $a $b ) {
$x = $y;
}
else {
$x = $z;
}
Thanks for any suggestions or guidance.
#
if ( @o_list ) {
if ( defined ( $o_list[2] ) ) {
$new_price = $o_list[2]-{price};
$new_price -= $new_price= 0 ? $new_price - .01 : 0;
}
}
if ( @o_list defined $o_list[ 2 ] ) {
$new_price = $o_list[ 2 ]{ price } / 0.8 + 15;
}
John
--
Any intelligent fool can make things bigger and
more complex... It takes a touch of genius -
and a lot of courage to move in the opposite
direction. -- Albert Einstein
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Re: XML::Twig Doubt
On 19/03/2012 15:12, Anirban Adhikary wrote:
Hi,
When I am trying to print the value against the tag ALPHA it is not prints
anything,though it is not showing any warnings.
use strict;
use warnings;
use XML::Twig;
my $twig = XML::Twig-new(start_tag_handlers = {
BSC = \on_BSC
});
sub on_BSC {
my($twig, $bsc)= @_;
print $bsc-id, \n;
my $alpha = $bsc-field('ALPHA');
print $alpha, \n;
$twig-purge;
}
$twig-parsefile(ISProducts.xml');
Hi List,
When I have changed the method
from my $twig = XML::Twig-new(start_tag_
handlers = {
BSC = \on_BSC
});
to
my $twig = XML::Twig-new(TwigHandlers = {
BSC = \on_BSC
});
I am able to print the value against the ALPHA tag.
Thanks to you for your support.
Hi Anirban
I suggested using start_tag_handlers because what you wanted to do was
extract the id attribute from the start tag of all BSC elements, so
there was no point in having any more of the element in store that just
that start tag. It is also more efficient
Changing to twig_handlers makes entirety of each twig (the BSC
element) available, so you are able to access the child elements as you
have found.
Rob
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Re: XML::Twig Doubt
On 19/03/2012 14:45, Anirban Adhikary wrote:
On Mon, Mar 19, 2012 at 7:41 PM, Rob Dixonrob.di...@gmx.com wrote:
XML::Twig uses callbacks to process pieces of the XML that you have
defined. In this case you are interested only in theBSC start tag so
you can define a start tag handler. Using $twig-purge empties the
data read so far. If you use this once you have accessed all the
information you need from a given element there is no need to store the
entire XML data in memory.
The program below doeas what I think you want.
HTH,
Rob
use strict;
use warnings;
use XML::Twig;
my $twig = XML::Twig-new(start_tag_**handlers = {
BSC = \on_BSC
});
sub on_BSC {
my($twig, $bsc)= @_;
print $bsc-id, \n;
$twig-purge;
}
$twig-parsefile('ISProducts.**xml');
Thanks for your support.The code does exactly what I want .
Can you please suggest me a tutorials with good examples on XML::Twig.
Another thing can you please explain me this line in the code my($twig,
$bsc)= @_;
When I am trying to print the value against the tag ALPHA it is not prints
anything,though it is not showing any warnings.
use strict;
use warnings;
use XML::Twig;
my $twig = XML::Twig-new(start_tag_handlers = {
BSC = \on_BSC
});
sub on_BSC {
my($twig, $bsc)= @_;
print $bsc-id, \n;
my $alpha = $bsc-field('ALPHA');
print $alpha, \n;
$twig-purge;
}
$twig-parsefile(ISProducts.xml');
Hi Anirban
I use the POD documentation supplied with the module, but I agree it is
a little opaque. XML::Twig has its own website at http://xmltwig.org
where you will find some tutorials that may help you.
The line
my ($twig, $bsc)= @_;
copies the values supplied as parameters to the callback into local
variables. $twig is the XML::Twig object itself, and $bsc is an
XML::Twig::Elt object representing the BSC XML element that has been
found.
You are unable to access the child elements of each BSC because I have
suggested you specify start_tag_handlers for which only the start tag
is available. That was fine when you just wanted the id attribute from
the tag, but there is no information about any other part of the XML.
You need to use twig_handlers instead, when the entire BSC element
will be accessible using
$bsc-first_child_trimmed_text('ALPHA')
HTH,
Rob
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Re: XML::Twig Doubt
Thanks a lot Rob for your nice help.
Best Regards
Anirban Adhikary.
On Tue, Mar 20, 2012 at 4:38 PM, Rob Dixon rob.di...@gmx.com wrote:
On 19/03/2012 14:45, Anirban Adhikary wrote:
On Mon, Mar 19, 2012 at 7:41 PM, Rob Dixonrob.di...@gmx.com wrote:
XML::Twig uses callbacks to process pieces of the XML that you have
defined. In this case you are interested only in theBSC start tag so
you can define a start tag handler. Using $twig-purge empties the
data read so far. If you use this once you have accessed all the
information you need from a given element there is no need to store the
entire XML data in memory.
The program below doeas what I think you want.
HTH,
Rob
use strict;
use warnings;
use XML::Twig;
my $twig = XML::Twig-new(start_tag_handlers = {
BSC = \on_BSC
});
sub on_BSC {
my($twig, $bsc)= @_;
print $bsc-id, \n;
$twig-purge;
}
$twig-parsefile('ISProducts.xml');
Thanks for your support.The code does exactly what I want
.
Can you please suggest me a tutorials with good examples on XML::Twig.
Another thing can you please explain me this line in the code my($twig,
$bsc)= @_;
When I am trying to print the value against the tag ALPHA it is not prints
anything,though it is not showing any warnings.
use strict;
use warnings;
use XML::Twig;
my $twig = XML::Twig-new(start_tag_**handlers = {
BSC = \on_BSC
});
sub on_BSC {
my($twig, $bsc)= @_;
print $bsc-id, \n;
my $alpha = $bsc-field('ALPHA');
print $alpha, \n;
$twig-purge;
}
$twig-parsefile(ISProducts.**xml');
Hi Anirban
I use the POD documentation supplied with the module, but I agree it is
a little opaque. XML::Twig has its own website at http://xmltwig.org
where you will find some tutorials that may help you.
The line
my ($twig, $bsc)= @_;
copies the values supplied as parameters to the callback into local
variables. $twig is the XML::Twig object itself, and $bsc is an
XML::Twig::Elt object representing the BSC XML element that has been
found.
You are unable to access the child elements of each BSC because I have
suggested you specify start_tag_handlers for which only the start tag
is available. That was fine when you just wanted the id attribute from
the tag, but there is no information about any other part of the XML.
You need to use twig_handlers instead, when the entire BSC element
will be accessible using
$bsc-first_child_trimmed_**text('ALPHA')
HTH,
Rob
Re: Perl Formula Help - Changing a Price in script
On 12-03-20 05:39 AM, John W. Krahn wrote: $x -= $y; Is short for: $x = $x - $y; It is borrowed from the C programming language. It would be more accurate to say it's equivalent to: $x = $x - ( $y ); This becomes important when using the multiplicative operators: $x *= $y + 1; Which means: $x = $x * ( $y + 1 ); -- Just my 0.0002 million dollars worth, Shawn Programming is as much about organization and communication as it is about coding. Show me your code and conceal your interfaces, and I shall continue to be mystified. Show me your interfaces, and I won't usually need your code; it'll be obvious. -- Fred Brooks [updated] -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
