Regular expression help 1

[mevasquez]

I have a string that contains a URL and I want to be able to remove everything in the URL except for the file name and assign this to a variable.

For example:
$URL = "

http://domainname.net/dir/subdir/filename.ext";

or
$URL = "

http://domainname.net/dir/subdir/subdir2/filename.ext";

There could be more than two subdirectories.

I need to remove all except filename.ext and assign this value to a variable called $filename.

I have been trying to use regular expression substitute to accomplish this but I am fairly new with regular expressions. Any help would be appreciated.

If using a regular expression to do this, could you explain so I could learn what is transpiring.

TIA,

Mike V

 

[Rieekan]

Try this:

my $url = "[URL unfurl="true"]http://somedomain.com/somedir/somedir/file.ext";[/URL]

#split on / and only grab the last element
my $filename = (split /\//, $url)[-1];

- Rieekan

 

[rharsh]

Or, if you really want to do it with a regex, though Rieekan's method is the way I'd go, you could use something like:

my $url = "[URL unfurl="true"]http://domainname.net/dir/subdir/subdir2/filename.ext";[/URL]
$url =~ m/
        .+\/        # Match as many characters as possible to last slash
        ([\w.]+)    # Grab all the word and . chars and put them in $1
        /x;         # Modifier allows for inline comments/whitespace

my $filename = $1;

I included comments for you, since you asked for them. You could modify it a bit if you wanted to use a substitution, but a match will work just fine.

 

[domster]

Won't that fail if the file has non-word characters (eg numbers or percent signs)? I would say:

$url =~ m|/([^/]*)$|;

#ie all the non-slash characters after the last slash up to the end of the string

$filename = $1;


Dom

 

[mevasquez]

I am using Rieekan's suggestion. It seems to work. I do have a question regarding regarding the reqular expression suggestions.

Where does $1 come from? Where is it assigned value?

Thanks,

Mike

 

[EBGreen]

$1..$n are assigned by the regex itself. Every instance of a pair of parenthesis () is assigned to $n in the order that they appear in the regex. In this case, the part of the string that matches this ([\w.]+) will be assigned to $1 since this is the first (and only) pair of parens.

[blue]"Well, once again my friend, we find that science is a two headed beast. One head is nice, it gives us aspirin and other modern conveniences,...but the other head of science is BAD! Oh, beware the other head of science, Arthur; it bites!!" - The Tick[/blue]

 

[mevasquez]

Thanks, understand $1.

Mike

 

[dchoulette]

Another way with regular expression:

($filename = $url) =~ s{.*/}{};
# set filename to url
# and/then supress all chars before last / in filename

--------------------

Denis