map { /(\d+)/; $1 }
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No, that is wrong.    If /(\d+)/ doesn't match then $1 will not contain valid data:

$ perl -le'
use Data::Dumper;
my @y = map { /(\d+)/; $1 } qw/ ab123cd ab456cd abcdefg ab789cd /;
print Dumper \@y;
'
$VAR1 = [
          '123',
          '456',
          undef,
          '789'
        ];
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Just use:

$ perl -le'
use Data::Dumper;
my @y = map /(\d+)/, qw/ ab123cd ab456cd abcdefg ab789cd /;
print Dumper \@y;
'
$VAR1 = [
          '123',
          '456',
          '789'
        ];
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The regular expression by itself will just do the right thing.