Question from perl newbie

I downloaded and installed Perl, seemingly in a successful manner to a
Windows XP computer. then I wrote the following code to a file,
Example_4_1.pl:

#! ..\bin\perl -w
$DNA = 'abc' ;
print $DNA ;
exit ;


Then, I run:

> perl Example_4_1.pl

The program seems to run without complaints, yet I don't see the output of
the print statement. What do I need to do to be able to see the output?

Thanks,
Victor

Victor

>The program seems to run without complaints, yet I don't see the output of
>the print statement. What do I need to do to be able to see the output?

Are you running it from a dos window or start -> run -> "perl
Example_4_1.pl" ? If you try the latter the window will close immediately
after the script finishes, hence you won't see the output.. You will want
to fire a dos prompt and from there you can run "perl Example_4_1.pl"..

Regards,
Chris

[X-Post and follow-up to CLPM because CLP has been a zombie for many years,
please see the FAQ]

Victor wrote:
> I downloaded and installed Perl, seemingly in a successful manner to a
> Windows XP computer. then I wrote the following code to a file,
> Example_4_1.pl:
>
> #! ..\bin\perl -w

Windows doesn't care about the shebang line. You can just as well leave it
out.
The command line option -w is outdated. It is better to use
use warnings;
instead.

> $DNA = 'abc' ;
> print $DNA ;
> exit ;

If exit is the last statement and you are not returning any special value
then you may just as well omit it.

> Then, I run:
>
>> perl Example_4_1.pl

Normally your Perl installation should have associated the .pl extension
with the Perl interpreter, such that you can run any Perl program by just
typing its name without calling the interpreter directly.

Example_4_1.pl

> The program seems to run without complaints, yet I don't see the
> output of the print statement. What do I need to do to be able to
> see the output?

That is weird. There is nothing wrong with your Perl code.
Maybe someone in CLPM knowns.

jue

am a newbie as well .. with exactly the same problem.

I have a file called "helloworld.pl". When it wouldnt put out any output
using <stdin> I decided to try to create and open a file and write to that.

____helloworld.pl________________________________
open(geo,">perltest.txt") or die ("Cannot Open perltest.txt");


for ($loop_index =1; $loop_index <=5; $loop_index++)
{
Print geo "hello world!\n"
}
Print "there!\n\n\n"
close (geo);
print "Press <enter> to continue" ;
<stdin>;
_____________________________________________
I then double clicked on the name and got the dos flicker .. but no file was
created.

so problem continues ... (new computer Windows XP .. and newly downloaded
ActivePerl seemingly sucessfully installed. )

Roy bramblet @ telus.net remove spaces.

----- Original Message -----
From: "Jürgen Exner" <>
Newsgroups: comp.lang.perl,comp.lang.perl.misc
Sent: Monday, December 18, 2006 8:05 AM
Subject: Re: Question from perl newbie


> [X-Post and follow-up to CLPM because CLP has been a zombie for many
> years, please see the FAQ]
>
> Victor wrote:
>> I downloaded and installed Perl, seemingly in a successful manner to a
>> Windows XP computer. then I wrote the following code to a file,
>> Example_4_1.pl:
>>
>> #! ..\bin\perl -w
>
> Windows doesn't care about the shebang line. You can just as well leave it
> out.
> The command line option -w is outdated. It is better to use
> use warnings;
> instead.
>
>> $DNA = 'abc' ;
>> print $DNA ;
>> exit ;
>
> If exit is the last statement and you are not returning any special value
> then you may just as well omit it.
>
>> Then, I run:
>>
>>> perl Example_4_1.pl
>
> Normally your Perl installation should have associated the .pl extension
> with the Perl interpreter, such that you can run any Perl program by just
> typing its name without calling the interpreter directly.
>
> Example_4_1.pl
>
>> The program seems to run without complaints, yet I don't see the
>> output of the print statement. What do I need to do to be able to
>> see the output?
>
> That is weird. There is nothing wrong with your Perl code.
> Maybe someone in CLPM knowns.
>
> jue
>

Roy Jaffray wrote:
> am a newbie as well .. with exactly the same problem.
>
> I have a file called "helloworld.pl". When it wouldnt put out any
> output using <stdin> I decided to try to create and open a file and
> write to that.
> ____helloworld.pl________________________________

You are missing
use strict;
use warnings;

> open(geo,">perltest.txt") or die ("Cannot Open perltest.txt");

It would be better to include the reason why the open failed.
.... or die ("Cannot Open perltest.txt because $!");
>
> for ($loop_index =1; $loop_index <=5; $loop_index++)

What's wrong with
for $loop_index (1..5)
Much easier to read

> {
> Print geo "hello world!\n"

Where to you define the funtion Print()?

> }
> Print "there!\n\n\n"

Where do you define the function Print()?

> close (geo);
> print "Press <enter> to continue" ;
> <stdin>;
> _____________________________________________
> I then double clicked on the name and got the dos flicker .. but no
> file was created.

Well, yeah, sure. Why don't you fix that syntax error that perl is telling
you about?

String found where operator expected at C:\tmp\t.pl line 8, near "Print
"there!\
n\n\n""
(Do you need to predeclare Print?)
syntax error at C:\tmp\t.pl line 8, near "Print "there!\n\n\n""
Execution of C:\tmp\t.pl aborted due to compilation errors.

> so problem continues ... (new computer Windows XP .. and newly
> downloaded ActivePerl seemingly sucessfully installed. )

Irrelevant. Your Perl code has a syntax error. Of course it doesn't produce
anything because it never even passed the syntax check.

jue

Roy Jaffray wrote:
> am a newbie as well .. with exactly the same problem.
>
> ____helloworld.pl________________________________

> I then double clicked on the name and got the dos flicker .. but no file was
> created.

Whenever clicking does not work, you should try running it from
the command line.

Start -> Run -> cmd
C:\> perl helloworld.pl

Fix the problems there first.
-Joe