How do I force list or scalar context in Perl?

I'm a little confused about some of the details of list and scalar contexts in Perl and I'm hoping someone can help me out a bit. My ultimate goal is to compare the number of elements in two arrays, except that one of the arrays is an anonymous array and I can't figure out to get Perl to tell me how many elements it has. This is what I typed into the debugger:`

DB<10> @a = ([1,2,3,4],[5,6,7,8,9],[10,11])

DB<11> @b = $a[1]

DB<12> $c = @b

DB<13> p $c
1             # Why didn't this print out 5?

DB<14> $d = $a[1]

DB<15> p @$d
56789

DB<16> p $$d
Not a SCALAR reference at (eval 17)[/opt/local/lib/perl5/5.8.9/perl5db.pl:638] line 2.

DB<17> @e = @a[1]

DB<18> p @e
ARRAY(0x87c358)

DB<19> p ${@e}

I'm out of combinations of funny characters to try, ca开发者_Python百科n someone please tell me what I'm doing wrong? Thanks.

[] will create an array reference (which is a scalar).

$a[1] points to [5,6,7,8,9] (the array reference)

@b = $a[1] will create a new array with one item in it (the array reference).

You need to dereference the arrayref.

@b = @{$a[1]}

At which point you can get the number of items in it:

print scalar @b