"use strict" and undeclared variables

padawan_linuxero has asked for the wisdom of the Perl Monks concerning the following question:

Hello I am newbie to Perl and DBI I have been working on
this code wish is a sample on how to view all data
from a mysql but here is the cuestion, everywhere they
told me to use strict, but everytime I try to run this program
it fail giving me this error message:

Global symbol "@row" requires explicit package name at conexionMySql2.pl line 13.
Global symbol "@row" requires explicit package name at conexionMySql2.pl line 14.

so I did the unthinkable I put a #on use strict and it
WORK!!!!

Can someone help me understanding why this is like this?
TIA

#!/usr/bin/perl

  use strict;
  use DBI();

  my $dbh = DBI->connect("DBI:mysql:database=test;host=localhost",
                         "root", "123xyz",
                         {'RaiseError' => 1});
   my $sth = $dbh->prepare("SELECT * FROM regtest");

  $sth->execute();
  
   while ((@row) = $sth->fetchrow_array()) {
      print "@row\n";
   }
  $sth->finish();
  $dbh->disconnect();
[download]

Comment on "use strict" and undeclared variables Download Code

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Re: "use strict" and undeclared variables by moritz (Cardinal) on Oct 11, 2007 at 14:31 UTC
With `use strict` in effect you have to declare variables. You can change your code to read `while (my @row = $sth->fetchrow_array()){` to fix it and still `use strict;`. Perl 6 in German	[reply] [d/l] [select]
Re: "use strict" and undeclared variables by toolic (Bishop) on Oct 11, 2007 at 14:36 UTC
In addition to what mortiz said, if you haven't already done so, read strict and my. That should give you a better understanding of why you should use strict and why you get this error. Also, you should: `use warnings;`	[reply] [d/l]
Re: "use strict" and undeclared variables by roboticus (Chancellor) on Oct 11, 2007 at 14:33 UTC
padawan_linuxero: perl was just telling you that you haven't declared @row. Declare it, and the warning will go away. `my @row;` [download] ...roboticus	[reply] [d/l]
Re: "use strict" and undeclared variables by ikegami (Patriarch) on Oct 11, 2007 at 19:46 UTC
so I did the unthinkable I put a # on use strict and it WORK!!!! It works in the sense that removing your shoe laces from your shoes will prevent you from tripping on them, but it'll make walking trickier.	[reply]
Re: "use strict" and undeclared variables by leocharre (Priest) on Oct 11, 2007 at 19:39 UTC
omfg.. yours is the funniest post i've seen in a long time.. It's because @row is not being declared.. that is.. it's not being told 'row exists in this area of the program'. keep using strict! Trust the strict- Strict is good- Strict is your friend. It's your girlfriend who loves you but won't put up with any of your 5h1+. If she whines and complains.. it means you need to stop that- or your code 'looks' like it's working.. but it's not. Like moritz suggested, this should work: `while ( my @row = $sth->fetchrow_array ) { print "@row\n"; }` [download] Again, what is happening is that you don't say anywhere 'my @row'. ~~You could also have done this.. (althought bad form and possibly buggy):~~ ~~`my @row; while ( @row = $sth->fetchrow_array ) { print "@row\n"; }`~~ ~~[download]~~ updateikegami suggests these snipplets are essentially the same, and that the second is not bad form or possibly buggy. And it was the # on strict that cracked me up. It's like when my two year old goges 'mommy i'm hot' so she pours a glass of cold organge juice all over herself and says 'now everything is great!'- that it's funny doesn't mean you have ill feelings for the situation.	[reply] [d/l] [select]
Re^2: "use strict" and undeclared variables by mjscott2702 (Pilgrim) on Oct 11, 2007 at 20:16 UTC
No need to be rude about it - as poster stated, they are a newbie to Perl. After all, asking questions, after having at least made an attempt, is how people LEARN.	[reply]
Re^2: "use strict" and undeclared variables by chrism01 (Friar) on Oct 12, 2007 at 00:37 UTC
What's bad/buggy about the latter? I always do that (hangover from C I guess). I prefer not to mix declarations and usage. Also, it means I can comment the declarations... Cheers Chris	[reply]
Re^3: "use strict" and undeclared variables by polettix (Vicar) on Oct 12, 2007 at 08:49 UTC
As a rule of thumb, you should try to restrict the scope of a variable as much as possible. The former restricts `@row` life to the `while` block, while the other goes beyond. Anyway, I wouldn't classify this neither as "bad" nor as "buggy". Flavio perl -ple'$_=reverse' <<<ti.xittelop@oivalf Io ho capito... ma tu che hai detto?	[reply] [d/l] [select]
Re^4: "use strict" and undeclared variables by blazar (Canon) on Oct 12, 2007 at 12:31 UTC
Re^4: "use strict" and undeclared variables by leocharre (Priest) on Oct 18, 2007 at 18:19 UTC