Extracting just the extension from a filename.

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

Replies are listed 'Best First'.
Re: Extracting just the extension from a filename. by ichimunki (Priest) on Jul 19, 2002 at 19:33 UTC
With a core module: File::Basename-- although this leaves the dot on the suffix, so you'll still want to use `s/^\.//` on the results on the call to fileparse().	[reply] [d/l]
Re: Extracting just the extension from a filename. by insensate (Hermit) on Jul 19, 2002 at 19:16 UTC
Try something like this: `my $fileName = "20020719.csv"; $fileName =~ /\.(\w+)$/; my $extension = $1;` [download] Jason	[reply] [d/l]
Re: Re: Extracting just the extension from a filename. by moxliukas (Curate) on Jul 19, 2002 at 19:25 UTC
This would work OK, but if the extension would contain some `funny' characters you could get into problem. It is not very often that you get extensions with spaces and other weird things, but hey, you never know. So my solution would be: `my $filename = '20020719.csv'; $filename =~ /\.([^\.]*)$/; my $extension = $1;` [download]	[reply] [d/l]
Re: Re: Extracting just the extension from a filename. by simeon2000 (Monk) on Jul 19, 2002 at 20:18 UTC
Good solution. My only additions would be to use \^\.\ instead of \w to catch \W as well but not ".". You could also one-line it by catching the matches with alist assignment to avoid reading from $1: `my ($extension) = $filename =~ /\.([^\.]+)$/;`	[reply] [d/l]
Re: Extracting just the extension from a filename. by thor (Priest) on Jul 20, 2002 at 16:23 UTC
In the spirit of TMTOWTDI: `my $fileName = "blah.csv"; my @array = split '\.', $fileName; print $array[-1],"\n";` [download] thor	[reply] [d/l]
Re: Extracting just the extension from a filename. by dug (Chaplain) on Jul 19, 2002 at 19:20 UTC
`$string =~ s/.\.(.)$/$1/;` [download] I'm certainly not a regex whiz, but this seems to do what you want. It will handles "."'s within the filename, and gives you the string after the last dot. HTH, dug	[reply] [d/l]
Re^2: Extracting just the extension from a filename. by Aristotle (Chancellor) on Jul 19, 2002 at 19:29 UTC
Why are you capturing the extension if you put it back into the string though? This works the same: `$string =~ s/^.[.]//;` But it has a problem: for files without an extension, it will return the full filename. If you want to do it with a subsitution rather than a match, it should be `$string =~ s/^.(?:[.]([^.]))?$/$2/;` This way the dot plus extension becomes optional; the base filename is still always erased. But it's so clumsy.. a match is more elegant: `my ($extension) = $string =~ /[.]([^.])$/;` Makeshifts last the longest.	[reply] [d/l] [select]
Re: Re^2: Extracting just the extension from a filename. by dug (Chaplain) on Jul 19, 2002 at 19:44 UTC
Why are you capturing the extension if you put it back into the string though? Too many spare cycles on my machine? Not enough caffine? <grin> Good point. Also, thanks for posting the more elegant solution.	[reply]
Re^4: Extracting just the extension from a filename. by Aristotle (Chancellor) on Jul 19, 2002 at 19:53 UTC
Re: Extracting just the extension from a filename. by krujos (Curate) on Jul 20, 2002 at 05:29 UTC
What about `$filename=~/\.(\S+)\s/` Just a thought...	[reply] [d/l]
Re: Re: Extracting just the extension from a filename. by krujos (Curate) on Jul 20, 2002 at 19:35 UTC
Why the down vote? At least explain what is so horrible about my solution please. Thanks	[reply]