RE: Re: Checking for Directories

Sorry, btrott, that won't work ... readdir() only returns basenames, and that's not enough for -d to work. Besides, you probably don't want to count '.' and '..'. How about:

my $dir = '/foo/bar';
opendir DH, $dir or die $!;
my @subdirs = grep { -d } map { "$dir/$_" }
              grep { $_ ne '.' && $_ ne '..' } readdir DH;
closedir DH;
[download]

-- Chip Salzenberg, Free-Floating Agent of Chaos

Comment on RE: Re: Checking for Directories Select or Download Code

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RE: RE: Re: Checking for Directories by mikfire (Deacon) on Jul 28, 2000 at 23:50 UTC
If the debugger is accurate, you are stepping through the array three times to produce your results. If you have a directory with a large number of files in it, this is not the most runtime-efficient way of doing it. This version makes a single pass through the directory listing. `#Assume all the open code foreach( readdir DH ) { next if ( $_ eq '.' or $_ eq '..' ); push @subdirs, "$dir/$_" if ( -d "$dir/$_" ); }` [download] Of course, you may still not like this. It will be kinda hungry on memory, especially if the ratio of files to directories is very large - the foreach will suck in every file at once. It may be better to try it with a while loop - it will be easier on memory but will take longer due to buffering issues. mikfire	[reply] [d/l]
Checking for Directories by chip (Curate) on Jul 29, 2000 at 00:30 UTC
Unless you've run it under `Benchmark`, you don't know whether your intuition is correct about which approach is faster. Besides, fewer lines of code and fewer variable names makes for easier maintenance, all things equal. -- Chip Salzenberg, Free-Floating Agent of Chaos	[reply] [d/l]
RE: RE: Re: Checking for Directories by btrott (Parson) on Jul 28, 2000 at 23:48 UTC
Oops. Thanks for the reminder. My test script was running in the same directory that I was opendir-ing. Stupid, but oh well. :)	[reply]