grep in list context (eg, used in a for) will create a new list by selecting elements in its input that match a condition. IE:

foreach (grep { $_ != 0 } @SlectedColumns[1..$NrCoumns])
{
  # Only non zero elements here
}
[download]

Edit: and if your input is only numbers, and the content of the loop is just one EXPR, you can even write: print "I'm priting $_!\n" for grep $_, @SlectedColumns[1..$NrCoumns];

I like this sort of pattern (update: maybe "style" would be a better word to use here than "pattern"):

c:\@Work\Perl\monks>perl -wMstrict -le
"my @SlectedColumns = (9, 7, 6, 0, 5, 0, 4, 3, 2, 0, 1, 9, 9);
 my $end_index = 10;
 ;;
 COLUMN:
 for my $col (@SlectedColumns[1 .. $end_index]) {
   next COLUMN unless $col != 0;
   print qq{do something with col $col};
   }
"
do something with col 7
do something with col 6
do something with col 5
do something with col 4
do something with col 3
do something with col 2
do something with col 1
[download]

Update 1: In my experience, this pattern turns up quite often in a context like:

use constant RX_COMMENT => qr{ ... }xms;
...
...
sub is_valid {
  
    my ($string,
        ) = @_;
        
    return
        $string =~ RX_COMMENT      ? 0 :
        $string =~ RX_BLANK_STRING ? 0 :
        $string =~ RX_VALID_LINE   ? 1 :
        die "invalid: '$string'"   # default
        ;
  
    }
...
...
LINE:
while (my $line = <$fh>) {

    next LINE unless is_valid($line);

    do_something_with_known_valid($line);
    do_something_else_with($line);
    ...

    }  # end while LINE
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Update 2: This is my 4000th writeup!

This is my 4000th writeup!

Congratulations. :)

This is my 4000th writeup!

I'm glad to have read many of them.

Cheers, Sören

Créateur des bugs mobiles - let loose once, run everywhere.
(hooked on the Perl Programming language)

you are looking for wisdom, not for elegance! ;=)

Elegance can be your enemy: better looking for efficiency and readability.

You already received a wise answer by Eily++ about grep

If your do_something is short as print you can consider also the unless postscript form:

foreach my $ele (@SlectedColumns[1..$NrCoumns]) {
        
       do_something unless $ele == 0;
}
[download]

It's an handy and readable syntax.

If the loop is complex and actions are more, something very similar to your example is a wise form to express some logic: a good principle exit loop early

foreach my $ele(@SlectedColumns[1..$NrCoumns]) {
     # exit soon
     next if $ele == 0;
     next unless defined $ele;
     ....        

    }
[download]

L*

"...one liner?..."

Probably you want something like this?

The stuff you want to do with $i goes here: ...; See also Common Causes for "Modification of a read-only value attempted".

Best regards, Karl

you can use map function in PERL to do a one line parsing of array. Below is an example which is similar to you code and you can extend to what ever you want to add in the if loop.

@tt = (1,2,3,5,0,7,8,9,10);
map{if($_!=0){print "I did something when it is not zero\n";}}@tt;
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But how is that better (in the sense of more clear or familiar) than, say,
    print "do something with $_ \n" for grep $_ != 0, @tt;
(already suggested by Eily here)?

---

Give a man a fish:  <%-{-{-{-<

First it is one liner. Second you can add logic you want under these parentheses map{....}@yourarray. But on your one liner with grep you are just doing a print "do something ...".