Hi Nora,
On Monday 27 September 2010 09:19:46 HACKER Nora wrote:
> Hello list,
>
> Could someone please explain why this test script:
>
> my @arr1 = qw(one two three);
> my @arr2 = qw(1 2 3);
>
> foreach my $arr1 ( @arr1 ) {
> print "Arr1: $arr1\n";
> foreach my $arr2 ( @arr2 ) {
> print "Arr2: $arr2\n";
> if ( $arr2 eq '2' ) {
> shift @arr1;
You shouldn't modify an array (@arr1 in this case) while iterating over it
using foreach. Otherwise, the results will be unpredictable. One option to
overcome it is to do:
[code]
my @arr1_copy = @arr1;
while (defined (my $arr1_elem = shift(@arr1_copy)))
{
# Do something with $arr1_elem
}
[/code]
This will not work properly if @arr1 contains undef elements but it's
relatively easy to fix:
[code]
while (@arr1_copy)
{
my $arr1_elem = shift;
}
[/code]
Regards,
Shlomi Fish
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