Getting the file extension and uppercasing it (Perl)

Question

How can I make this piece of my code terser (in one line) but still understandable.

 ($ext) = $ARGV[0] =~ /(\.[^.]+)$/;
 $ext=~s/^.//s;
 $ext=uc $ext;

It gets the file extensions, remove the dot and then uppercase it.

in: asldaldjlajdlk.torrent
out: TORRENT

score 4 · Answer 1 · answered Aug 07 '14 at 23:41

4

I think I'd probably use something like:

my $ext = ($ARGV[0] =~ /\.(\w+)$/) ? uc($1) : undef;

Adjust undef to be whatever you'd like the default value of $ext to be when the regexp fails to match.

answered Aug 07 '14 at 23:41

tobyink

Miller · Answer 2 · 2014-08-07T23:57:09.863

3

You've chosen a pattern that will not always match.

I therefore suggest using a ternary to be able to explicitly specify your undefined value.

my $ext = $ARGV[0] =~ /\.([^.]+)$/ ? uc($1) : '';

edited Aug 07 '14 at 23:57

answered Aug 07 '14 at 23:41

Miller

+1, I was thinking along the lines of `(my $ext = $ARGV[0]) =~ s/^.*\.([^.]+)$/\U$1/;` – hwnd Aug 07 '14 at 23:49
My first thought was to do `(my $ext = uc $ARGV[0]) =~ s/.*\.//;`. However that would change the definition of what's an extension. – Miller Aug 07 '14 at 23:55
Yeah I see what you mean. – hwnd Aug 07 '14 at 23:56

score 1 · Answer 3 · answered Aug 08 '14 at 06:49

1

$v is your input

($m = uc $v) =~ s/(\w+)\.(\w+)/$2/g;

answered Aug 08 '14 at 06:49

pkm

score 0 · Answer 4 · edited May 23 '17 at 12:21

0

Removing my answer, this is discussed here: Inline regex replacement in perl

The furthest I got was this:

($ext = uc $ARGV[0]) =~ s/^.*\.([^.]+)$/$1/;

edited May 23 '17 at 12:21

Community

answered Aug 07 '14 at 23:35

Alien Life Form

1

No, it won't. Plus it has the side-effect of altering `$ARGV[0]`. – tobyink Aug 07 '14 at 23:39
I just realized that. Updating my answer, but it's not a bit improvement. – Alien Life Form Aug 07 '14 at 23:41
\1 won't work on the RHS of a substitution in Perl. $1 is used instead. – Slade Aug 08 '14 at 00:36
1

@Slade: It will work, but it's discouraged because it's ambiguous – Borodin Aug 08 '14 at 01:30

score 0 · Answer 5 · edited Aug 23 '20 at 19:19

0

I think I would ignore the possibility that a file name may not contain a dot, and write

(my $ext = uc shift) =~ s/.*\.//

If there is a dot in the name, this leaves $ext set to the upper-cased file extension (everything after the last dot).
Otherwise $ext is set to the whole upper-cased file name.

edited Aug 23 '20 at 19:19

HoldOffHunger

answered Aug 08 '14 at 01:32

Borodin

5 Answers5