What is the difference between if( -f $f ) and unless( -d $f )?

[hsk]

#!/usr/bin/perl -w

use File::Find;

my ( @dirs, $sum, $cnt, $dirname, $base_dir );

$base_dir = "D:\\temp";

find(\&wanted, $base_dir);

sub wanted {

$name = $File::Find::name;


if( -d $name )
{
push( @dirs, $name );
}
}


foreach my $d ( @dirs )
{

opendir( DIR, $d );

# set back to 0 size
$sum = 0;


foreach my $f ( readdir( DIR ) )
{
# set back to 0 size
$size = 0;

# if( -f $f )
unless( -d $f )
{
$size = (stat($f))[7];
$sum = $sum + $size;
}
}
close( DIR );

}

There is no error in case of 'if( -f $f ), but gets some errors for
'unless( -d $f )'. The error comes up in the line of '$sum = $sum + $size'
, saying 'Use of Uninitialized value.'
Is there any of who might give an answer for this?

OS: window 2000, ActivePerl 5.8 version

 

[Gunnar Hjalmarsson]

hsk wrote:

[ Subject:
What is the difference between if( -f $f ) and unless( -d $f )? ]

You should get some hints if you check out "perldoc -f -X".

 

[Tony Curtis]

On 25 Oct 2004 19:07:52 -0700,

# if( -f $f ) unless( -d $f ) { $size = (stat($f))[7]; $sum
= $sum + $size;

There is no error in case of 'if( -f $f ), but gets some
errors for 'unless( -d $f )'. The error comes up in the line
of '$sum = $sum + $size' , saying 'Use of Uninitialized
value.' Is there any of who might give an answer for this?

Well, firstly -f and -d don't cover the entire file type
space, so the 2 tests you have don't trap all possible cases.

Secondly, you don't check whether the stat() succeeded, which
is more likely to be the root cause of your woes.

You can also write

$sum += $size;

to be more succinct.

hth
t

 

[A. Sinan Unur]

(e-mail address removed) (hsk) wrote in

What is the difference between if( -f $f ) and unless( -d $f )?

Please do not only put your question in the subject line.

see perldoc -f -x

Sinan

 

[Jürgen Exner]

hsk wrote:

Subject: What is the difference between if( -f $f ) and unless( -d $f )?

Uhh, I would say sockets, symbolic links, named pipes, devices, just to name
a few more common ones.

jue