why does this perl routine error?

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

This gives an error that states that I split an unintialized value, why? I declared all variables and i just gave split a string to parse. I am not familiar with these errors so far since I am trying to script with warnings and strict from now on to become a better programmer. I am sorry for asking question so regularly however I am not have a huge trouble figuring these things error. Thank you so much in advance.

use LWP::Simple;
use List::Util 'max';
use strict;
use warnings;



stockquotegetter();



sub stockquotegetter
{

my (@quotes,$html,@aandelen,@url,@url1,@url2,$aandeel,%stockhash1);
$html = get("http://www.iex.nl/Koersen/Aandelen.aspx")
  or die "Couldn't fetch the stock quotes";
@aandelen = qw(Aegon Air Ahold Aperam Akzo ASML ArcelorMittal ING Bosk
+alis Corio DSM Fugro Heineken KPN Philips PostNL Randstad Reed  Royal
+ SBM TNT TomTom Wolters Unilever);
foreach $aandeel (@aandelen)
{
print "$aandeel";
@url = split(/Realtime koers $aandeel/, $html);


 @url1 = split(/LastPrice"><span>/, $url[1]);
 @url2 = split(/</, $url1[1]);
printf "$aandeel $url2[0]\n";
push (@quotes,$url2[0]);
$stockhash1{ $aandeel } = $url2[0];

#eval for hourly


}
#print @quotes;
return %stockhash1;
#print %stockhash1;
}
[download]

Comment on why does this perl routine error? Download Code

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Re: why does this perl routine error? by toolic (Bishop) on Sep 07, 2012 at 20:40 UTC
The 1st "Use of uninitialized value in split" warning message you get is because the @url array does not have more that one element. Therefore, `$url[1]` is undefined. You can prove this to yourself by adding this debug line: `@url = split( /Realtime koers $aandeel/, $html ); print scalar(@url), "\n"; # show number of elements in array` [download] See also: Basic debugging checklist You should consider using an HTML parser.	[reply] [d/l] [select]
Re: why does this perl routine error? by jethro (Monsignor) on Sep 07, 2012 at 20:42 UTC
You have more than one split in there. If the first split can't split because the search string isn't found then the complete string would be in `$url[0]`. Consequently `$url[1]` would be undef. Same for @url1	[reply] [d/l] [select]
Re^2: why does this perl routine error? by robertw (Sexton) on Sep 07, 2012 at 20:45 UTC
Thank I will look into this now:) I am happy when i finally program with strict and warnings on since I can declare lexicals strictly and make easily reusable modules:)	[reply]
Re^3: why does this perl routine error? by Anonymous Monk on Sep 07, 2012 at 21:03 UTC
Well, there is a right way and a wrong way to do lexicals, declaring them all up front is the wrong way see Tutorials: Variable Scoping in Perl: the basics, Coping with Scoping , Mini-Tutorial: Perl's Memory Management, Lexical scoping like a fox	[reply]
Re: why does this perl routine error? by kcott (Archbishop) on Sep 08, 2012 at 07:52 UTC
"I am not familiar with these errors so far since I am trying to script with warnings and strict from now on to become a better programmer." Try using the diagnostics pragma for more descriptive error messages: `use strict; use warnings; use diagnostics;` [download] As an example, I posted this earlier today: `$ perl -Mstrict -Mwarnings -le 'for (0..1) { our $x = $_ } print $x' Variable "$x" is not imported at -e line 1. Global symbol "$x" requires explicit package name at -e line 1. Execution of -e aborted due to compilation errors.` [download] This is probably not overly useful if you've just started learning Perl; however, with `diagnostics` you get a more verbose explanation of the problems: $ perl -Mstrict -Mwarnings -le 'use diagnostics; for (0..1) { our $x = + $_ } print $x' Variable "$x" is not imported at -e line 1 (#1) (W misc) With "use strict" in effect, you referred to a global var +iable that you apparently thought was imported from another module, beca +use something else of the same name (usually a subroutine) is exported + by that module. It usually means you put the wrong funny character o +n the front of your variable. Global symbol "$x" requires explicit package name at -e line 1. Execution of -e aborted due to compilation errors (#2) (F) You've said "use strict" or "use strict vars", which indicates + that all variables must either be lexically scoped (using "my" or +"state"), declared beforehand using "our", or explicitly qualified to say which package the global variable is in (using "::"). Uncaught exception from user code: Global symbol "$x" requires explicit package name at -e line 1. Execution of -e aborted due to compilation errors. at -e line 1. [download] See also: perldiag -- Ken	[reply] [d/l] [select]
Re: why does this perl routine error? by Anonymous Monk on Sep 07, 2012 at 20:28 UTC
You know why :) because the variable is undef, obviously	[reply]
Re^2: why does this perl routine error? by robertw (Sexton) on Sep 07, 2012 at 20:37 UTC
But $url1 has a value, how can it be undef if it has a value?@url does not generate an error if i print it and gives the html but $url does and still gives me a value:SS	[reply]
Re^3: why does this perl routine error? by Anonymous Monk on Sep 07, 2012 at 20:40 UTC
But $url1 has a value, how can it be undef if it has a value? How do you know? As Basic debugging checklist says, use Dumper, show the output	[reply]