Re: Find the last item in a series of files

I'm a bit reluctant to sort a whole array if all that is needed is to find a maximum value, because the algorithmic complexity is higher (meaning it is in theory less efficient). Having said that, I must admit it probably does not matter unless then number of file is very high.

Anyway, you might avoid a sort with something like this:

my %hash
for my $file (glob("*.*")) {
    my ($root, $ext) = split /\./, $file;
    if (defined $hash{root) {
        $hash{$root} = $ext if $ext > $hash{$root};
    } else {
        $hash{$root} = $ext;
    }
}
[download]

The if ... else statement could be reduced to a simple if statement and a Boolean operator:

$hash{$root} = $ext if (not defined $hash{$root}) or $ext > $hash{$roo
+t};
[download]

but I wanted to make it as easy to read as possible.

Comment on Re: Find the last item in a series of files Select or Download Code

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Re^2: Find the last item in a series of files by Marshall (Canon) on Jun 16, 2017 at 23:54 UTC
A simple split to two parts may not be enough depending upon the OP's filenames and how many '.' characters might be contained within those names. I think that a regex assignment would be more appropriate instead of a split. But it could be that this is all the OP needs. I don't like your one line if..else because it is "hard to understand" and confers no execution advantage. Anyway, a nice algorithm idea that compares favorably with the HoA ideas previously posted.	[reply]
Re^3: Find the last item in a series of files by Laurent_R (Canon) on Jun 17, 2017 at 09:21 UTC
I agree with you. I chose `split` on the basis of the example provided in the OP (file.001, file.002, ...). A regex would be more robust for more complex filenames. I also think that the one-line version of the if ... else statement is less easy to understand (that's why I used the other version in the complete code version), I only wanted to show it could also be made more concise.	[reply] [d/l]
Re^3: Find the last item in a series of files by CountZero (Bishop) on Jun 22, 2017 at 05:54 UTC
A simple split to two parts may not be enough depending upon the OP's filenames and how many '.' characters might be contained within those names. I think that a regex assignment would be more appropriate instead of a split. But it could be that this is all the OP needs. That's why using File::Basename seems a good idea as it provides an easy interface to extract path, files-basename and extension. CountZero A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James My blog: Imperial Deltronics	[reply]
Re^4: Find the last item in a series of files by Marshall (Canon) on Jun 22, 2017 at 22:13 UTC
Yes, File::Basename is a fine idea. But that won't get you out of providing a regex in this particular situation. The functions either take a list of strings like ".txt". ".doc". Or a regex in qr// form. Of course the enumerated suffix strings are the easiest way to use these functions. However, in this particular situation with varying numeric suffixes, ".001", etc., I would think a regex is needed even if using File::Basename.	[reply]
Re^5: Find the last item in a series of files by CountZero (Bishop) on Jun 24, 2017 at 08:16 UTC


Think about Loose Coupling
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