On 8/26/07, lists user <[EMAIL PROTECTED]> wrote:
> I run a perl command below,
>
> perl -Mstrict -Mwarnings -e 'eval {my $x=3;my $y=$x-3;$x/$y};print "hello"'
> Useless use of division (/) in void context at -e line 1.
> hello
>
> I'm confused about the first warning.What's it?thanks.
Let's break this down and see what is going on:
perl -MO=Deparse -Mstrict -Mwarnings -e 'eval {my $x=3;my
$y=$x-3;$x/$y};print "hello"'
Useless use of division (/) in void context at -e line 1.
use warnings;
use strict 'refs';
eval {
do {
my $x = 3;
my $y = $x - 3;
$x / $y
}
};
print 'hello';
-e syntax OK
>From this we can see that the result of $x/$y is not used. Perl is
warning you that this is "useless". However, it is not exactly
useless as it is triggering a divide by zero error in the eval. The
way to get rid of this warning is to make sure the result is used by a
function or assigned to a variable:
perl -Mstrict -Mwarnings -e 'eval {my $x=3;my $y=$x-3; my $z =
$x/$y};print "hello"'
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