path extraction

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

Hi perl peeps, I am trying to figure how this regex works:

/usr/bin/perl
/usr/bin/ 
/perl 
/ 
perl
[download]

if ($string =~ m#(\S*/)(\S*)#) {     
   print "Path = $1, $Filename = $2\n"; 
} 
elsif ($string =~ /(\S+)/) {     
   print "No path, Filename = $1\n"; 
}
[download]

Ok thanks everyone and for ur examples;

so in my example where the inbetween: (\S*)(\S*), does this cause the regex to jump down to the next line as there is just whitepace after the first capture/match?

Edit: g0n - code tags

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Re: path extraction by ikegami (Patriarch) on Dec 09, 2007 at 21:04 UTC
Perl already comes with that functionality in the form of `fileparse` in File::Basename.	[reply] [d/l]
Re: path extraction by GrandFather (Saint) on Dec 09, 2007 at 20:41 UTC
Bottom line - it doesn't! \S matches non-whitespace characters and * means 'grab as many as you can', but if your path or filename contains whitespace characters then things turn a little pear shaped. Consider instead: `use strict; use warnings; for my $string ( '/Unixish path/with/spaces in places/and a file name with spaces', 'file name only - with spaces', '/nice/no/spaces/path/and/filename' ) { if ($string =~ m!(./)?(.)!) { print "Path = '$1', Filename = '$2'\n"; } elsif ($string =~ /(\S+)/) { print "No path, Filename = '$2'\n"; } }` [download] Prints: `Path = '/Unixish path/with/spaces in places/', Filename = 'and a file +name with spaces' Path = '', Filename = 'file name only - with spaces' Path = '/nice/no/spaces/path/and/', Filename = 'filename'` [download] In any case you would generally be better to use File::Spec's `splitpath`. Perl is environmentally friendly - it saves trees	[reply] [d/l] [select]
Re: path extraction by mwah (Hermit) on Dec 09, 2007 at 20:31 UTC
You need to modify the regex a little bit, like: `... my @strings = qw' /usr/bin/perl /usr/bin/ /perl / perl '; for my $string (@strings) { if( $string =~ m{^(./)(.)$} ) { print "Path = $1, Filename = $2\n"; } elsif( $string =~ m{^([^/]+)$} ) { print "No path, Filename = $1\n"; } } ...` [download] (One variant of many, close to your original program.) Regards mwa	[reply] [d/l]