perl 5.12新功能，有一个each命令，但是这个按照教材来的不行，求解释

唔.. 错不在 each , 而是第一句要写成
my @rocks = qw/ ........... / ;
因为当你 use 5.012 时, 就暗示了同时 use strict
即每个变数第一次使用前都要 my, 或者 our ( 如果你准备 export 的话 )

可以啊，我的文件de.pl
#! /usr/perl/bin
@rocks=qw/barny betty emma nicole/;
while(my ($index,$value) = each @rocks)
{
print "$index : $value \n";
}

D:\>perl de.pl
0 : barny
1 : betty
2 : emma
3 : nicole

http://perldoc.perl.org/5.12.0/functions/each.html

each HASH

each ARRAY

When called in list context, returns a 2-element list consisting of the key and value for the next element of a hash, or the index and value for the next element of an array, so that you can iterate over it. When called in scalar context, returns only the key (not the value) in a hash, or the index in an array.

Hash entries are returned in an apparently random order. The actual random order is subject to change in future versions of Perl, but it is guaranteed to be in the same order as either the keys or values function would produce on the same (unmodified) hash. Since Perl 5.8.2 the ordering can be different even between different runs of Perl for security reasons (see Algorithmic Complexity Attacks in perlsec).

After each has returned all entries from the hash or array, the next call to each returns the empty list in list context and undef in scalar context. The next call following that one restarts iteration. Each hash or array has its own internal iterator, accessed by each, keys, and values. The iterator is implicitly reset when eachhas reached the end as just described; it can be explicitly reset by calling keys or values on the hash or array. If you add or delete a hash's elements while iterating over it, entries may be skipped or duplicated--so don't do that. Exception: It is always safe to delete the item most recently returned by each(), so the following code works properly:

while (($key,$value) = each%hash){
print$key,"\n";
delete$hash{$key};
# This is safe
}

This prints out your environment like the printenv(1) program, but in a different order:

while (($key,$value) = each%ENV){
print"$key=$value\n";
}