Perl Guru Forums: Perl Programming Help: Beginner: Getting Parameters with a Loop, Use several $var(x) in a loop

CGI/Perl Guide | Learning Center | Forums | Advertise | Login

Site Search: in


	MAIN INDEX	SEARCH POSTS	WHO'S ONLINE	LOG IN

Home: Perl Programming Help: Beginner:
Getting Parameters with a Loop, Use several $var(x) in a loop

Rivotti
User

Mar 30, 2000, 5:33 AM

Post #1 of 6 (438 views)

Getting Parameters with a Loop, Use several $var(x) in a loop	Can't Post

Hi:
I created a form with 10 fields. To get the parameters a need to use the lines:
<BLOCKQUOTE>code:<HR>

$var1= param('field1');
$var2= param('field2');
$var3= param('field3');
$var4= param('field4');
$var5= param('field5');
...
$var10= param('field10');
</pre><HR></BLOCKQUOTE>
Is it possible to do this operation with a loop? like:
<BLOCKQUOTE>code:<HR>

for ($j=1; $j<=10; $j++)
{ $var(number)= param('field(number)'); }</pre><HR></BLOCKQUOTE>

The same way, can I use all the parameters using a loop? like :
<BLOCKQUOTE>code:<HR>

for ($j=1; $j<=10; $j++)
{ print "$var(number)\n"; }</pre><HR></BLOCKQUOTE>

Please make it possible.
Rivotti

japhy
Enthusiast

Mar 30, 2000, 8:12 AM

Post #2 of 6 (439 views)

Re: Getting Parameters with a Loop, Use several $var(x) in a loop [In reply to]	Can't Post

You're asking about symbolic references:

<BLOCKQUOTE>code:<HR>

for $i (1 .. 10) { # a loop, Perl-style
${"var$i"} = param("field$i");
}
</pre><HR></BLOCKQUOTE>

Now that you've seen it, don't use it! Symbolic references are "left over" from Perl 4 before there was any means of real references (hard references). But the point here is that if you have a list of variables, $foo1, $foo2, $foo3, etc., you should use an array.

<BLOCKQUOTE>code:<HR>

@var = map param("field$_"), 1 .. 10;

# then you can do
print $var[3]; # since arrays start at 0, $var[3] is param("field4")
</pre><HR></BLOCKQUOTE>

That map() function is rather useful, and saves you from doing a loop with a for() statement instead:

<BLOCKQUOTE>code:<HR>

for (1 .. 10) {
push @var, param("field$_");
}
</pre><HR></BLOCKQUOTE>

Rivotti
User

Mar 30, 2000, 2:13 PM

Post #3 of 6 (438 views)

Re: Getting Parameters with a Loop, Use several $var(x) in a loop [In reply to]	Can't Post

Hi japhy:

I've tried what you told me to do but I got the following error:

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

Another thing:
I have the variable $xtime=4 and i want to get @var param $xtime. Then test each one of $var - unless(!$var[number]) - and then print each one. All of this in a loop. Is it possible?

Thanks
Rivotti

Cure
User

Mar 30, 2000, 2:42 PM

Post #4 of 6 (438 views)

Re: Getting Parameters with a Loop, Use several $var(x) in a loop [In reply to]	Can't Post

Hi

you need this at the top of your cgi-script
use CGI qw(:standard);
to pevent the Undefined subroutine &main::param called at ...

use CGI qw(:standard) -> this will import ":standard" set of function definitions into your cgi-script.

Cure

Rivotti
User

Mar 31, 2000, 12:29 AM

Post #5 of 6 (438 views)

Re: Getting Parameters with a Loop, Use several $var(x) in a loop [In reply to]	Can't Post

Thanks, you found the "Cure" for my problem

Rivotti
User

Mar 31, 2000, 1:45 AM

Post #6 of 6 (438 views)

Re: Getting Parameters with a Loop, Use several $var(x) in a loop [In reply to]	Can't Post

What if I'm getting variables form a file using require "file.pl"?
<BLOCKQUOTE>code:<HR>

$text1="text1";
$text2="text2";
$text3="text3";
$text4="text4";
...
$text10="text10";</pre><HR></BLOCKQUOTE>
Is there a way to teste if the var is empty and, if not, print the var text?
Something similar to this:
<BLOCKQUOTE>code:<HR>

for ($j=1; $j<=10; $j++)
{ unless(!$text[number])
{ print $text[number] }
}</pre><HR></BLOCKQUOTE>

I'm sure this code is not correct. Is there a correct way of doing this. This is a simple example: The program I'm working have 20 variables. As you can see it's important to know this to avoyd writing useless lines to my program

Thank you very much
Rivotti

Search for (options)

Web Applications & Managed Hosting Powered by Gossamer Threads
Visit our Mailing List Archives