On Tue, Oct 28, 2003 at 10:51:20PM +0100, B. Fongo wrote:
> What may be wrong with my codes? Perl complains of use of uninitialized
> value at addition and in range (or flop).
>
> #!/usr/bin/perl -w
> use strict;
>
> my ($xi, $i, @numbers, @slice);
> @numbers = (1..10);
> $i = 0;
> $xi = 0;
>
> open(RS, ">perd.dat") || die "Could not open file. $!\n";
> for (my $z = 0; $z <= $#numbers; $z++){
> foreach (@numbers){
> @slice = @numbers[$xi, $numbers[$i] .. $numbers[$i]+4];
> # Use of uninitialized value at here?
> print RS "@slice\n";
> $i++;
> }
> $xi++;
> }
You could write it more cleanly like this:
my $path = 'perd.dat';
open my $rs, $path or die "open: $path: $!";
my @numbers = 1..10;
for my $z (0..$#numbers) {
for my $i (0..$#numbers) {
print $rs @numbers[$z, $numbers[$i]..$numbers[$i]+4];
}
}
Which gets rid of some of the unused variables and uses the more
perlish foreach() loop. The problem is that you're indexing off
the end of @numbers -- I assumed that you meant to reset $i each
time through the outer loop (?) which fixes part of the problem,
but you still have the situation where $i > 4.
Look at the result of this expression when $z = 0 and $i = 5.
print $rs @numbers[$z, $numbers[$i] .. $numbers[$i] + 4];
--> print $rs @numbers[ 0, $numbers[5] .. $numbers[5] + 4];
--> print $rs @numbers[ 0, 6 .. 6 + 4];
--> print $rs @numbers[ 0, 6 .. 10 ];
--> print $rs @numbers[ 0, 6, 7, 8, 9, 10 ];
So the array slice yields:
--> print $rs 1, 7, 8, 9, 10, undef;
And this generates an "uninitialized value" warning.
The next time through the inner loop, you end up with:
print $rs @numbers[0, 7 .. 11]
--> print $rs @numbers[0, 7, 8, 9, 10, 11]
--> print $rs 1, 8, 9, 10, undef, undef;
Which generates two warnings, and so forth.
What are you really trying to do here?
--
Steve
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
