variable scope

[sonet]

The code print file in directory.But i have a question about the
variable scope.

Directory tree:
file: /usr/local/app/f1
file: /usr/local/app/f2
dir: /usr/local/app/d1
dir: /usr/local/app/d1/d2

If i use opendir(DIR,$path) not opendir(my $DIR,$path). The code
will terminate. Becase the FILEHANDLE closed as the main loop is
running.

When the code run at /usr/local/app/d1 , It have not terminate.
It will call self(recursive).Why the variable($path) in main loop
will not influence each other?

------------------------------------------------------------------------------------
my $dir='/usr/local/app';
listdir("$dir");

sub listdir{
my $path=shift;
opendir(my $DIR,$path);
while(my $file=readdir($DIR)){
if (-f "$path/$file"){
print "$path/$file\n";
}elsif (-d "$path/$file" && $file ne '.' && $file ne '..'){
listdir("$path/$file");
}
}
close($DIR);
}

 

[Brian McCauley]

opendir(my $DIR,$path);

close($DIR);

Tad has addressed your actual question but I would like to point out
that close() above does nothing. Potentially $DIR (which is a GLOBref)
actually holds both a filehandle and a directory handle (and a scalar,
and an array and so on...). Of these potential things only the
directory handle is used.

To close the directory handle.

closedir($DIR);

But if you are not checking for failure anyhow you may as well not
bother. It'll be closed implicitly when the last reference to the GLOB
goes away. Unless you've made any persistant copies this'll be when
$DIR goes out of scope.

 

[Joe Smith]

If i use opendir(DIR,$path) not opendir(my $DIR,$path). The code
will terminate. Becase the FILEHANDLE closed as the main loop is
running.

opendir(DIR,$path);
while(my $file=readdir(DIR)){

You're using readdir() in scalar context. That does not work when
a single dirhandle is being used in a recursive manner.

If you insist on using DIR instead of a lexical variable, you should
use it and close it before any recursion takes place.

opendir(DIR,$path) or die;
my @files = readdir(DIR);
close DIR:
foreach my $file (@files) {


-Joe