Strings

[hunter13605]

I am writing a program to find the mode of a group of numbers. I want to send a string of numbers from gerdata.pl to save.pl.

This is the form code from getdata.pl
#-----------------------------------------------------------
print"<TABLE>
<FORM ACTION=save.pl METHOD='post'>
<INPUT TYPE='hidden' NAME='size' VALUE=$size>";

for($i = 1; $i <= ($size); ++$i)
{
print "
<TR BGCOLOR='beige' valign='top'>
<TD><FONT FACE='arial' SIZE='2' COLOR='black'><div align='left'>$i</TD>
<TD><FONT FACE='arial' SIZE='2' COLOR='black'><div align='left'><INPUT TYPE='textbox' SIZE='5' NAME='number[$i]' VLAUE=$number[$i]></TD>
</TR>";
}

print "</TABLE>";
print "<INPUT TYPE='submit' VALUE='FIND RESULTS'>";
print "</FORM>";
#----------------------------------------------------------

This is the code that i am using to recieve the string. It dosen't appear to work.
#-----------------------------------------------------------
$size= $query->param('size');
for($i = 1; $i <= ($size); ++$i)
{
$number[$i]= $query->param('number[$i]');
}
#-----------------------------------------------------------

I am getting the number of numbers on the string and then using a for loop to recieve the numbers. In my mind and in c++ files that i have written it would seem that it should work perfectly but i can't seem to get it to work. Please help.

 

[KevinADC]

hmmm.... can't figure out what you are trying to do. Must be the Friday afternoon want-to-go-out-and-party blues.


What is ($size) supposed to be?


for($i = 1; $i <= ($size); ++$i)

and where does $number[$i] come from?


lines like these won't work:

$number[$i]= $query->param('number[$i]');

because you have $i inside of single-quotes which kills variable interpolation.

 

[hunter13605]

Basically, I am getting a list of number (The length defined by size) and i want to save this list to a text file. Is there a way that i can tell the form to send them to that text file.

I am trying to write a program that will take in a list of numbers and return the mode. I know it is easy to do it with just looking at the list with my own eyes but the assignement was to write a program that did it.

You can see what i have done at

http://www.match.nnysitedeisgns.net/cgi-bin/TEST/test.pl

 

[KevinADC]

bad link you posted but I figured it out. Like I said, the single-quotes are killing the variable interpolation. Try this:

$size= $query->param('size');
for($i = 1; $i <= ($size); ++$i)
  {
   $number[$i]= $query->param("number[$i]");
  }

but that is an awkward syntax "number[$i]" because it so closely resembles $number[$i], it looks like a syntax error. I would dispense with the number[] part of the name attribute and just use "number". You can use CGI.pm to retrieve the number fields as a list:

my @numbers = $query->param('number');

 

[hunter13605]

Thanks for the help. The whole world of perl is new to me so i am still learning. I see what you mean. That does look like a syntax error to me also. I have gotten a lot of them. I have seen the '@' symbol used before in different code i have looked at but never understood what it did. Could you please explain what CGI.pm means and what the @ symbol does

 

[KevinADC]

In your code you have:

$query->param('size');

this means you must already be using the CGI.pm module, something like:

use CGI;
$query = new CGI;

if not, your script will error out with something like:

Undefined subroutine &main:aram called at.......

CGI.pm is a core perl module used for parsing CGI form data and generating HTML code and some more:

http://perldoc.perl.org/CGI.html

it's a big module and does lots of things and the documentation can be confusing at first but take it a little at a time and you will understand how to use it.

Perl has three basic data types:

$string (scalar)
@array (array: a list of scalars)
%hash (hash: a special array with key/value pairs)

 

[hunter13605]

I do use those two lines in every file

use CGI;
$query = new CGI;

I got a book that said that you need to do that at the beginning of every file.

I am guessing that i want to use an array. I have been working with c++ for the last 2 years and have found that there are many similarities between the two.

So what i need to know is:
1. do i need to sent the size of the array to the save file?
2. in the form how would i send the array? This is the form code that i have right now.

print"<TABLE>
  <FORM ACTION=save.pl METHOD='post'>
  <INPUT TYPE='hidden' NAME='size' VALUE=$size>";
  
  for($i = 1; $i <= ($size); ++$i)
  {
print "
   <TR BGCOLOR='beige' valign='top'>
   <TD><FONT FACE='arial' SIZE='2' COLOR='black'><div align='left'>$i</TD>
   <TD><FONT FACE='arial' SIZE='2' COLOR='black'><div align='left'><INPUT TYPE='textbox' SIZE='5' NAME='number[$i]' VLAUE=$number[$i]></TD>
  </TR>";
  }
  
print "</TABLE>";
print "<INPUT TYPE='submit' VALUE='FIND RESULTS'>";
print "</FORM>";

 

[KevinADC]

you can do this to print the form:

print"<TABLE>
  <FORM ACTION='save.pl' METHOD='post'>
  <INPUT TYPE='hidden' NAME='size' VALUE=$size>";
  
  for my $i (1 .. $size)
  {
print "
   <TR BGCOLOR='beige' valign='top'>
   <TD><FONT FACE='arial' SIZE='2' COLOR='black'><div align='left'>$i</TD>
   <TD><FONT FACE='arial' SIZE='2' COLOR='black'><div align='left'><INPUT TYPE='textbox' SIZE='5' [b]NAME='number'[/b] [b]VALUE='$i'[/b]></TD>
  </TR>";
  }
  
print "</TABLE>";
print "<INPUT TYPE='submit' VALUE='FIND RESULTS'>";
print "</FORM>";

Then in save.pl:

use CGI;
use strict;
my $query = new CGI;
my @numbers = $query->param('number');
my $sum_of_numbers = 0;
foreach my $number (@numbers) {
   $sum_of_numbers += $number;
}
print $query->header,$query->start_html;
print "The sum of the numbers is: $sum_of_numbers";
print $query->end_html;

 

[hunter13605]

I will try that. Thanks for your help.