I know this is really dumb and basic but I can't figure it out.

#!/usr/bin/perl -w

use strict;

my @string = qw/Jessy Bob Nancy/;
my $num = 0;
while ( $num < @string ) {
    print "$string[$num] ";
    $num++;
}

### or, instead of a loop, just:

print "\n@string\n";
[download]

I'm trying to make a CGI script that will take two form fields and let a user enter in an unlimited amount of data points. For instance they will select a city and distance, then a second city and distance, then a third... etc..

You can see by executing my code what I'm trying to do, I just can't get the values from one submission to another to stay.

Any ideas?

#!/usr/bin/perl -w

use CGI::Carp qw(fatalsToBrowser);
use strict;
use CGI;

my $cgi = CGI->new();

my $city1 = $cgi->param("city");  # Get a fresh warning point
my $distance1 = $cgi->param("distance");

my @parameterNames = $cgi->param;
my $numCity = 0;  #Counter for all the Cities passed back to the scrip
+t

foreach(@parameterNames){
  if(/city/) { #Check each paramater to see if is a "city" is present
    $numCity++;  #If it is a city, add it to the counter
  }
}


print $cgi->header;

my $action = "help.pl";
print $cgi->start_form(-action=>$action);

my $quit = '1';#Once this # gets high enough, the loop "quits"
 if ($numCity){ #If there are any cities, print them as hidden fields
  while($quit <= $numCity) {

#    my $hiddenCity = "\$city".$quit;
#    my $hiddenCityValue = eval $hiddenCity;

#    my $hiddenDistance = "\$distance".$quit;
#    my $hiddenDistanceValue = eval $hiddenDistance;

    my $hiddenCityName = "city".$quit;
    my $hiddenDistanceName = "distance".$quit;

    my $hiddenCityValue = $cgi->param("$hiddenCityName");
    my $hiddenDistanceValue = $cgi->param("$hiddenDistanceName");

   print $cgi->hidden("$hiddenCityName", "$hiddenCityValue");
   print $cgi->hidden("$hiddenDistanceName", "$hiddenDistanceValue");

   print "$hiddenCityName => $hiddenCityValue<br>";
   print "$hiddenDistanceName=> $hiddenDistanceValue<br><hr>";
   $quit++;
  }
}

print <<EOF;
<select name="city" tabindex="1">
<option value="1">Columbus</option>
<option value="2">Chicago</option>
</select>
&nbsp&nbsp&nbspDistance:&nbsp<input type="text" name="circularWarningD
+istanceStart" size="6" maxlength="6" />
<br>
EOF

print $cgi->submit('Go');
print $cgi->end_form;
[download]

In this particular situation, it looks like you just want to concatenate your cities and distances to those already chosen. You could use a single hidden field for each, something like:

my @cities,@distances;
if ($cgi->param('hiddenCities')) { # there are cities and distances
                                   # from before
    @cities = split(';',$cgi->param('hiddenCities'));
    @distances = split(';',$cgi->param('hiddenDistances'));
}
if ($cgi->param('Go')) { # form was submitted
    push @cities,$cgi->param('city');
    push @distances,$cgh->param('circularWarningDistanceStart');
}
# put list of cities back on the form
print $cgi->hidden('hiddenCities',join(';',@cities);
print $cgh->hidden('hiddenDistances',join(';',@distances);
# ....
# do more form stuff here
# like asking for more input, etc.
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The code above is untested, but I hope that gives you some ideas you could use.

Sean

This is what was retunred when I ran your code with perl -w:

Global symbol "$string" requires explicit package name at math1.pl lin
+e 10.
Execution of math1.pl aborted due to compilation errors.
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You would have found out the issue very easily by yourself, if you have warnings on.

What you want is an array, and it is a bad idea to do what you are trying to do (and I am not going down the eval path):

use strict;
use warnings;

my @strings = ("Jessy", "Bob", "Nancy");
for (@strings) {
    print $_, "\n";
}
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use warnings;
use strict;

use strict;

my $string0 = "Jessy";
my $string1 = "Bob";
my $string2 = "Nancy";

my $num = 0;

while( $num != 3 ) {
  print eval "\$string$num";
  $num++
}
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In this case you could:

my @strings = ("Jessy", "Bob", "Nancy");
print join "", @strings;
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for example. There are many other way to do this!

You want to eval

is this what you want?

#!/usr/bin/perl -w

use strict;

my $string0 = "Jessy";
my $string1 = "Bob";
my $string2 = "Nancy";

my $num = 0;

while( $num != 3 ) {
  print eval ('$string' . $num),$/;
  $num++;
}
__END__
Jessy
Bob
Nancy
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use strict;

my $string0 = "Jessy";
my $string1 = "Bob";
my $string2 = "Nancy";

for my $num (0..3) {
  no strict 'refs'; # Thanks for the correction, tinita
  print "${qq(string$num)}\n";
}
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no strict 'references';

uhm... Unknown 'strict' tag(s) 'references' at -e line 2
you meant no strict 'refs' i guess =)

Why it's stupid to `use a variable as a variable name' part 1 2 3

my $string0 = "Jessy";
my $string1 = "Bob";
my $string2 = "Nancy";

my $num = 0;
while( $num < 3 ) {
  my $stringnum = "\$string" . $num;

  my $result = eval $stringnum;
  print $result . "\n";
  $num++;
}
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This produces the following output:

Jessy
Bob
Nancy
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  my $stringnum = "\$string" . $num;

  my $result = eval $stringnum;
[download]

(Note: I gave monarch a chance to fix his own article in /msg, but he blew me off in /msg and is now ignoring me, so I have to make this a public comment instead. I think that qualifies as "trying to do the right thing first".)

Please don't use eval for this without adding a big "don't do this, though". It invokes the compiler needlessly, and it also encourages variable variables, which is a broken form of programming.

I'd elaborate, but other answers in this thread already have better solutions. I just needed to flag monarch's solution as bad since he was unwilling to do that himself.

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.