"use strict" and undeclared variables

[padawan_linuxero]

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();

[moritz]

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;.

[toolic]

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;

[roboticus]

padawan_linuxero:

perl was just telling you that you haven't declared @row. Declare it, and the warning will go away.

my @row;

...roboticus

[ikegami]

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.

[leocharre]

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";
   }

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";
}

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.

[mjscott2702]

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.

[chrism01]

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

[polettix]

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".