How do I extract a substring from this string?

Question

I have a string that looks like: /somedir/ref/some-dir/foo.word

How could I extract foo from the above string? The whole string, including foo may vary, however, the structure is always the same. It will always the letters between the last slash and the last dot.

Answer 1

It looks like you're trying to find the filename (without extension) from a fully-qualified file path. If this is the case, then look into the File::Basename core module:

my $str = "/somedir/ref/some-dir/foo.word";
my( $filename, $directory, $suffix ) = fileparse($str, qr/\.[^.]*/);

The fileparse() method takes two arguments: the string to be parsed and the file suffix to be removed. If you don't know what the file suffix is going to be beforehand, then you can supply a regular expression. In this case, the suffix will match a period followed by zero or more non-period characters.

Edit: And if you're not finding filenames, and want the letters between the last / and the last ., try this:

my $str = "/somedir/ref/some-dir/foo.word";
my @elems1 = split '/', $str;
my @elems2 = split '\.', $elems1[-1];
my $foo = $elems2[-2];

TIMTOWTDI! :-)

Answer 2

my ($foo) = $str =~ m|/(\w+)[^/]+$|;

That assumes the "foo" part can consist of any "word" characters (alphanumeric plus underscore).

Answer 3

try this

s/.*\/([^.]*)\..*/$1/g

Answer 4

Try

if ($str =~ /\/([^\/]+)\.[^\/]*?$/) {
    $foo = $1; # This is the word 'foo' in your test case.
} else {
    die("Error matching string");
}

Demonstration (using Ruby, but the regex is the same in both languages): http://www.rubular.com/r/7FUeFFV4QI

Edit: Fixed a bug

Answer 5

$str =~ m/\/(\w+)\./

foo will be stored in the special $1 variable in perl. If you want it in a normal variable after just assign it.

$myvar = $1;

This is easily the simplest solution listed so far.

This will extract any word string between "/" and "." in the input. It will always be the word you want, unless there is multiple periods in the string to match against. But I am assuming "." will only be at the end (like on a file extenstion).

Answer 6

#!/usr/bin/perl

use strict; use warnings;

my $s = '/somedir/ref/some-dir/foo.word';

if ( my ($x) = $s =~ m{/(\w+)\.\w+\z} ) {
    print "$x\n";
}