Assign section of variable to another variable in Perl using regexp

Question

If I had

my $ip = "10.9.8.X";

and I want $IPCore to have "10.9.8". Is there an easy way to do this in a single line?

I usually do this

my $ip = "10.9.8.X";
my $IPCore = $ip;
$IPCore =~ s/([0-9]{3}\.[0-9]{3}\.[0-9]{3})\.[xX]{1,3}$/$1/

##$IPCore is now 10.9.8

Is there an easier way to do this?

Thank you

ikegami · Accepted Answer · 2016-06-15 18:58:33Z

2

Short solution to remove the last . and everything after it:

( my $IPCore = $ip ) =~ s/\.[^.]*\z//;
my $IPCore = $ip =~ s/\.[^.]*\z//r;                        # 5.14+

Optimized solution to remove the third . and everything after it:

( my $IPCore = $ip ) =~ s/^[^.]*+(?:\.[^.]*+){2}\K.*//s;   # 5.10+
my $IPCore = $ip =~ s/^[^.]*+(?:\.[^.]*+){2}\K.*//sr;      # 5.14+

edited Jun 15, 2016 at 18:58

answered Jun 15, 2016 at 17:47

ikegami

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Rooster · Accepted Answer · 2016-06-15 18:00:59Z

0

Assuming you trust the IPs will come in a reasonable format, a really simple approach is just to cut off the last segment from the last .(dot) like so:

 my $ip = '10.9.8.x';
 (my $ipCore = $ip) =~ s/(.*?)\.[^.]+$/$1/;
 print $ipCore;
//yields '10.9.8'

answered Jun 15, 2016 at 18:00

Rooster

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score 0 · Accepted Answer · 2016-06-15 22:30:38Z

0

3 birds, 1 stone

my ($ip, $IPCore) = ("10.9.8.X");
print $IPCore if $ip =~ /([0-9]{1,3}(?:\.[0-9]{1,3}){2})\.[xX]{1,3}$(?{$IPCore=$^N})/;

Out 10.9.8

edited Jun 15, 2016 at 22:30

answered Jun 15, 2016 at 22:24

user557597

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