foreach not a global variable?

jriggs420 has asked for the wisdom of the Perl Monks concerning the following question:

#!/usr/bin/perl -w
use Cwd;
       
opendir(DIR, ".");
@files = readdir(DIR);
closedir(DIR);
my $file;
my $i=0;
foreach $file (@files) {
        if ($file=~ /^(rs|rp|re|tv|pr|do)[0-9]{7}$/){$job=$file;
        print "$job\n";}#prints $job's value no problem       
       
        if (undef $job) {print "Job file not found! Check directory!\n
+";exit;}#passes this  

$cwd = cwd();
#my $job=$job;#just trying some stuff--
print $job."\n";#blank
print "$cwd\nrand can only be used in a 'projects' folder!\n";
if ($cwd !~ /\/script\/projects\/$job/){exit;}
[download]

I get the use of uninitialized variable in the last line ($job) which doesn't make sense to me because I call it later on in the script, and it is there! Any ideas? TIA

Comment on foreach not a global variable? Download Code

Replies are listed 'Best First'.
Re: foreach not a global variable? by dragonchild (Archbishop) on Apr 21, 2006 at 20:23 UTC
`if ( ! defined $job ) { ... }` [download] undef() is a function that sets any variable passed to it to undef. My criteria for good software: Does it work? Can someone else come in, make a change, and be reasonably certain no bugs were introduced?	[reply] [d/l]
Re: foreach not a global variable? by GrandFather (Saint) on Apr 21, 2006 at 22:46 UTC
`undef` is a function that sets a variable to undefined as already pointed out by DragonChild. What you are after is `defined` which tests to see if a variable is defined so the code you want is: `if (! defined $job) {#passes this print "Job file not found! Check directory!\n";exit; }` [download] However there is another subtle thing going on here that you should be aware of. You declare `my $file` outside a for loop which uses `$file` as the loop variable. Take particular note that the contents of `$file` are only valid inside the loop and that `$file` is an alias to the items in `@files` that the loop iterates over. This is not causing a problem in the code you show, but is important to remember. Especially because when you change the contents of a loop variable you are actually changing element of the list that the loop variable is currently aliased to. In you code that means that changing the contents of `$file` inside the loop changes the contents of an element of `@files`. DWIM is Perl's answer to Gödel	[reply] [d/l] [select]
Re: foreach not a global variable? by jwkrahn (Abbot) on Apr 21, 2006 at 22:18 UTC
You probably want something like: `#!/usr/bin/perl -w use strict; use Cwd; my $dir = '/script/projects'; opendir DIR, $dir or die "Cannot open directory '$dir' $!"; my ( $job ) = grep /^(?:r[spe]\|tv\|pr\|do)\d{7}$/, readdir DIR; defined $job or die "Job file not found! Check directory!\n"; # etc.` [download]	[reply] [d/l]