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variable declaration and countdown

jazzo
Novice

Aug 25, 2012, 10:41 AM

Post #1 of 4 (1418 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 (1415 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
Veteran / Moderator

Aug 25, 2012, 11:05 AM

Post #3 of 4 (1414 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 (1410 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!

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