Question

I am trying to parse the filename from paths. I have this:

my $filepath = "/Users/Eric/Documents/foldername/filename.pdf";
$filepath =~ m/^.*\\(.*[.].*)$/;
print "Linux path:";
print $1 . "\n\n";
print "-------\n";

my $filepath = "c:\\Windows\eric\filename.pdf";
$filepath =~ m/^.*\\(.*[.].*)$/;
print "Windows path:";
print $1 . "\n\n";
print "-------\n";

my $filepath = "filename.pdf";
$filepath =~ m/^.*\\(.*[.].*)$/;
print "Without path:";
print $1 . "\n\n";
print "-------\n";

But that returns:

Linux path:

-------
Windows path:Windowsic
                      ilename.pdf

-------
Without path:Windowsic
                      ilename.pdf

-------

I am expecting this:

Linux path:
filename.pdf
-------
Windows path:
filename.pdf
-------
Without path:
filename.pdf
-------

Can somebody please point out what I am doing wrong?

Thanks! 🙂

Answer 1

Well, the answer to what is happening would be: various errors.

my $filepath = "/Users/Eric/Documents/foldername/filename.pdf";
$filepath =~ m/^.*\\(.*[.].*)$/;
print "Linux path:";
print $1 . "\n\n";
print "-------\n";

$filepath doesn’t have any \\s in it, so it won’t match and there’s no $1. You put /s in it. Your expression would have to be:

# regular expression matches return their captures in a list context.
my ( $path ) = $filepath =~ m|/([^/.]*\.[^/.]*)$|;
print "Linux path:$path\n\n-------\n"; # little need to . a " string

my $filepath = "c:\\Windows\eric\filename.pdf";
$filepath =~ m/^.*\\(.*[.].*)$/;
print "Windows path:";
print $1 . "\n\n";
print "-------\n";

You’re using double quotes, which, taking their cue from UNIX shells, are more active than single quote strings. Thus, you need to escape all your backslashes, like this:

my $filepath = "c:\\Windows\\eric\\filename.pdf";

or just use single quotes:

my $filepath = 'c:\Windows\eric\filename.pdf';

Actually, since perl understands '/' for windows, this works too (but not for the regex.)

my $filepath = "c:/Windows/eric/filename.pdf";

As long as you fix it before handing it back to Windows.

my $filepath = "filename.pdf";
$filepath =~ m/^.*\\(.*[.].*)$/;
print "Without path:";
print $1 . "\n\n";
print "-------\n";

This didn’t match, so $1 is still the last match. That’s why it’s repeated. But this points up the value of catching the captures instead of referring to $1.