Re: usage of "my" keyword

You have use strict; so you must declare variables or the error you see will be thrown. If you've copied/paste this without understanding I suggest you read and understand strict. An alternative would be to declare $i within the for loop.

"How to merge these three lines"

One way to write this:

use strict;
use warnings;

my $number=8;

for( my $i=0; $i<20; $i++ ){
    print "present value of the number is: $number\n";
    $number++;
}
[download]

If you are new to perl the following links will likely be of interest:

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Re^2: usage of "my" keyword by ravi45722 (Pilgrim) on Aug 10, 2015 at 09:28 UTC
Here if i use my keyword for number its scope is also available in other functions. I want to restrict the scope of number. Thanks for reply	[reply]
Re^3: usage of "my" keyword by Laurent_R (Canon) on Aug 10, 2015 at 10:07 UTC
No, if you declare $i inside the `for` loop the way marto has shown, the scope of $i will be only the `for` loop itself, not outside that block. Consider this example: `$ perl -E 'for( my $i=0; $i<10; $i++ ){say "Inside loop: $i";} say "Ou +tside loop: $i";' Inside loop: 0 Inside loop: 1 Inside loop: 2 Inside loop: 3 Inside loop: 4 Inside loop: 5 Inside loop: 6 Inside loop: 7 Inside loop: 8 Inside loop: 9 Outside loop:` [download] You can see that the value of $i is not defined outside the loop. And if I add the warnings, I get: `... Inside loop: 9 Use of uninitialized value $i in concatenation (.) or string at -e lin +e 1. Outside loop:` [download]	[reply] [d/l] [select]
Re^3: usage of "my" keyword by AnomalousMonk (Archbishop) on Aug 10, 2015 at 12:31 UTC
I want to restrict the scope of number. It's not clear to me, but it seems possible you're actually asking "I want to restrict the scope of the `$number` scalar." If that's the case, then one way is to establish an independent scope `{ ... }` for the variable: c:\@Work\Perl\monks>perl -wMstrict -le "my $number = 42; print '$number before independent scope == ', $number; ;; { my $number = 8; print '$number in independent scope == ', $number++ for 1 .. 5; } ;; print '$number after independent scope == ', $number; " $number before independent scope == 42 $number in independent scope == 8 $number in independent scope == 9 $number in independent scope == 10 $number in independent scope == 11 $number in independent scope == 12 $number after independent scope == 42 [download] Update: Discussions of scoping can be found throughout perlsyn and among the Tutorials in the Variables and Scoping section. Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re^3: usage of "my" keyword by ikegami (Patriarch) on Aug 10, 2015 at 14:47 UTC
Here if i use my keyword for number its scope is also available in other functions. I want to restrict the scope of number. What other functions???	[reply]