perl

zahheb · 08-20-2012, 11:37 PM

sub int_all {
my @retlist = @_; # make safe copy for return
for my $n (@retlist) { $n = int($n) }
return @retlist;
}

friends i am not able to understand the meaning of the

for my $n (@retlist) { $n = int($n) }

please help

Tinkster · 08-21-2012, 12:14 AM

Neither do I ... it iterates over all array elements, sticking
each as it passes into the scalar $n, puts an integer version
of the value back into it, and overwrites it on each run w/o
having done anything w/ the new value.

In other words: apart from wasting a few CPU cycles it does nothing.

Cheers,
Tink

gregAstley · 08-21-2012, 04:28 AM

Quote:

Originally Posted by zahheb

sub int_all {
my @retlist = @_; # make safe copy for return
for my $n (@retlist) { $n = int($n) }
return @retlist;
}

friends i am not able to understand the meaning of the

for my $n (@retlist) { $n = int($n) }

please help

Mu knowledge of Perl isn't so great but...
I tested this and (assuming an integer cast makes sense) it is converting whatever happens to be in @retlist to ints (the $ns are handles on the actual array values and so whats actually happening is something like $retlist[some index] = int($retlist[some index])). Try this bit of code to see:

Code:

#!/usr/bin/perl
use strict;
use warnings;

my @array = (1.4, 3.167, 1.5);
for my $n(@array)
{
    print "\n\$n was: $n";
    $n = int($n);
    print "\n\$n is now: $n"
}

result:

$n was: 1.4
$n is now: 1
$n was: 3.167
$n is now: 3
$n was: 1.5
$n is now: 1

zahheb · 08-21-2012, 04:59 AM

so can we also write it as

for each $n (@array) {...}

instead of for $n (@array) {....}

gregAstley · 08-21-2012, 05:13 AM

Quote:

Originally Posted by zahheb

so can we also write it as

for each $n (@array) {...}

instead of for $n (@array) {....}

not quite...change "for each" to "foreach" (never used it yet but "each" is a key word used in a different context) you might also want to fling a "my" infront of "$n"

zahheb · 08-21-2012, 05:48 AM

yes foreach.......

by the way ,each is also used to traverse through the elements of an array

gregAstley · 08-21-2012, 06:01 AM

Quote:

Originally Posted by zahheb

yes foreach.......

by the way ,each is also used to traverse through the elements of an array

Thanks for letting me know...we've both learnt something today :]

zahheb · 08-21-2012, 06:35 AM

thanks to u too

Tinkster · 08-21-2012, 04:26 PM

Quote:

Originally Posted by gregAstley

Mu knowledge of Perl isn't so great but...
I tested this and (assuming an integer cast makes sense) it is converting whatever happens to be in @retlist to ints (the $ns are handles on the actual array values and so whats actually happening is something like $retlist[some index] = int($retlist[some index])). Try this bit of code to see:

Code:

#!/usr/bin/perl
use strict;
use warnings;

my @array = (1.4, 3.167, 1.5);
for my $n(@array)
{
    print "\n\$n was: $n";
    $n = int($n);
    print "\n\$n is now: $n"
}

result:

$n was: 1.4
$n is now: 1
$n was: 3.167
$n is now: 3
$n was: 1.5
$n is now: 1

I learnt something to; I didn't realise that the loop variable is actually
a reference to the actual array elements.

Cheers,
Tink