Re: Recursion

[James Edward Gray II]

On Sunday, November 2, 2003, at 06:19 AM, Rob Dixon wrote:

Jeff Westman 
wrotenews:[EMAIL PROTECTED]
Hi,

I've never liked "recursion" but of course there are times where it is
needed.
I'm not sure I would say recursion is "needed", but it sure makes some 
things simpler.  I've never met a recursive function I couldn't rewrite 
iteratively though, often with some pain, of course.

Hi Jeff.

File::Find would do it for you, but the revursion is very
simple really:
  use strict;
  use warnings;
  printdir('/usr');

  sub printdir {

    my $dir = shift;

    opendir DIR, $dir or die $!;
    my @dirs = grep /[^.]/, readdir DIR;
    closedir DIR;
    foreach (map "$dir/$_", @dirs) {
      if (-d) {
        printdir($_);
      }
      elsif (-f _) {
        print $_, "\n";
      }
    }
  }
# or iteratively...

sub printdir {
        my @dirs = (shift);
        
        while (@dirs) {
                my $dir = shift @dirs;
                opendir DIR, $dir or die "Directory error:  $!";
                my @new_dirs = grep /^[^.]/, readdir DIR;
                closedir DIR;
                
                foreach (map "$dir/$_",@new_dirs) {
                        if (-d) { push @dirs, $_; }
                        elsif (-f _) { print "$_\n"; }
                }
        }
}
James

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