There is no such thing as "array mode" in Perl.    I believe you are refering to "list context"?

([0-9]{3}|[0-9]{2}|[0-9]{1}) could be written more simply as [0-9]{1,3} and it will also avoid the unnecessary capturing parentheses.

use strict;
use warnings;

my @lines = ("ip:192.168.243.1", "ip:192.168.243.2" =~ /(ip:([0-9]{3}|
+[0-9]{2}|[0-9]{1})\.([0-9]{3}|
+[0-9]{2}|[0-9]{1})\.([0-9]{3}|[0-9]{2}|[0-9]{1})\.([0-9]{3}|[0-9]{2}|
+[0-9]{1}))/);

print "@lines\n";
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It looks like you want something like:

use strict;
use warnings;

my @lines = ( "ip:192.168.243.1", "ip:192.168.243.2" );

for ( @lines ) {
    print "$1\n" if /(ip:[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3
+})/;
    }
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