Perl - add a variable in a variable

Question

I want add the variable $hostname in the variable $hostame_table appended with _table.

My code:

use Sys::Hostname ();
my $hostname = Sys::Hostname::hostname();
my $hostname_table = "$hostname"+"_table";
print "$hostname_table";

I would like the result to be computername_table.

From perlop: Binary "+" returns the sum of two numbers. Binary "." concatenates two strings. — Matt Jacob
– Matt Jacob, Commented Nov 13, 2018 at 21:35

Dave Cross · Accepted Answer · 2018-11-13 16:34:22Z

5

What you're looking for here is called "string concatenation". Perl uses a dot (.) as the concatenation operator, not the + which you've tried to use.

$hostname_table = $hostname . '_table';
print $hostname_table;

Update: Another common approach would be to just "interpolate" the values in a double-quoted string.

$hostname_table = "$hostname_table"; # This doesn't work.

Unfortunately, this simple approach doesn't work here as "_table" is valid as part of a variable name and, therefore, Perl doesn't know where your variable name ends. You can get around that by using a slightly more complex syntax which wraps the variable name in { ... }.

$hostname_table = "${hostname}_table";

edited Nov 13, 2018 at 16:34

answered Nov 13, 2018 at 16:27

Dave Cross

69.5k3 gold badges55 silver badges101 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

stevieb Over a year ago

Perhaps throw in a blurb about interpolation as well (I was going to but you've already got the first part done): my $hostname_table = "${hostname}_table";

Dave Cross Over a year ago

@stevieb: I considered it, but the need for {...} in this case made it slightly more complicated than I wanted to explain. I'll give it a go :-/

stevieb Over a year ago

You don't have to, it was just a thought ;)

Dave Cross Over a year ago

@stevieb: Done.

stevieb Over a year ago

++. I just thought it would round out the answer is all.

Collectives™ on Stack Overflow

Perl - add a variable in a variable

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related