Perl Guru Forums: Perl Programming Help: Beginner: variable declaration and countdown

CGI/Perl Guide | Learning Center | Forums | Advertise | Login

Site Search: in


	MAIN INDEX	SEARCH POSTS	WHO'S ONLINE	LOG IN

Home: Perl Programming Help: Beginner:
variable declaration and countdown

jazzo
Novice

Aug 25, 2012, 10:41 AM

Post #1 of 4 (663 views)

variable declaration and countdown	Can't Post

Hi peeps, I came across this simple script:

Code

 
#!/usr/bin/perl 
# countdown.plx 
use warnings; 
use strict; 
my @count = (1..5); 
for (reverse(@count)) { 
print "$_...\n"; 
sleep 1; 
} 
print "BLAST OFF!\n";

and I was wondering, shouldn't the variable

Code

reverse

be declare as

Code

my reverse

rather than using it without declaring it?
The the other thing. to print off the numbers we say:

Code

print "$_...\n";

why do we use "$_"?
can we not use the array something like

Code

print "$count[reverse]\n";

thanks

(This post was edited by jazzo on Aug 25, 2012, 10:48 AM)

FishMonger
Veteran / Moderator

Aug 25, 2012, 11:03 AM

Post #2 of 4 (660 views)

Re: [jazzo] variable declaration and countdown [In reply to]	Can't Post

reverse is not a variable. It's one of perl's built-in functions.

http://perldoc.perl.org/functions/reverse.html

Laurent_R
Enthusiast / Moderator

Aug 25, 2012, 11:05 AM

Post #3 of 4 (659 views)

Re: [jazzo] variable declaration and countdown [In reply to]	Can't Post

Hi,

reverse is not a variable, but a function that reverse the order of the @count array (makes it 5 4 3 2 1).

In the for loop, the default variable $_ is assigned successively to the reversed values of @count.

You could write this more explicitly:

Code

foreach my $number (reverse @count) { 
    print "$number...\n"; 
     sleep 1; 
} 
print "BOOOOM\n";

jazzo
Novice

Aug 25, 2012, 11:23 AM

Post #4 of 4 (655 views)

Re: [Laurent_R] variable declaration and countdown [In reply to]	Can't Post

of course it is a function, what a donkey I am, sorry!

Search for (options)

Web Applications & Managed Hosting Powered by Gossamer Threads
Visit our Mailing List Archives