Question

sub do_printf  { printf @_ }
sub do_sprintf { print sprintf @_ }

do_printf("%s\n", "ok");  # prints ok
do_sprintf("%s\n", "ok"); # prints 2

Answer 1

From the perldoc on sprintf:

Unlike printf, sprintf does not do
what you probably mean when you pass
it an array as your first argument.
The array is given scalar context, and
instead of using the 0th element of
the array as the format, Perl will use
the count of elements in the array as
the format, which is almost never
useful.