How can I filter an array without using a loop in Perl?

Question

Here I am trying to filter only the elements that do not have a substring world and store the results back to the same array. What is the correct way to do this in Perl?

$ cat test.pl use strict; use warnings;  my @arr = ('hello 1', 'hello 2', 'hello 3', 'world1', 'hello 4', 'world2');  print "@arr\n"; @arr =~ v/world/; print "@arr\n";  $ perl test.pl Applying pattern match (m//) to @array will act on scalar(@array) at test.pl line 7. Applying pattern match (m//) to @array will act on scalar(@array) at test.pl line 7. syntax error at test.pl line 7, near "/;" Execution of test.pl aborted due to compilation errors. $ 

I want to pass the array as an argument to a subroutine.

I know one way would be to something like this

$ cat test.pl  use strict; use warnings;  my @arr = ('hello 1', 'hello 2', 'hello 3', 'world1', 'hello 4', 'world2'); my @arrf;  print "@arr\n";  foreach(@arr) {     unless ($_ =~ /world/i) {        push (@arrf, $_);      } } print "@arrf\n";  $ perl test.pl hello 1 hello 2 hello 3 world1 hello 4 world2 hello 1 hello 2 hello 3 hello 4 $ 

I want to know if there is a way to do it without the loop (using some simple filtering).

Answer 1

That would be grep():

#!/usr/bin/perl  use strict; use warnings;  my @arr = ('hello 1', 'hello 2', 'hello 3', 'world1', 'hello 4', 'world2'); my @narr = ( );  print "@arr\n"; @narr = grep(!/world/, @arr); print "@narr\n"; 

Answer 2

Use grep:

sub remove_worlds { grep !/world/, @_ } 

For example:

@arrf = remove_worlds @arr; 

Using grep is the most natural fit for your particular problem, but for completeness, you can also do it with map:

sub remove_worlds { map /world/ ? () : $_, @_ } 

It's a bit klunky here, but map gives you a hook in case you want to process the filtered elements before discarding them.