my %foo = 1 .. 10;
while(my($k,$v) = each %foo){
    print "k($k)v($v)\n";
}

while(my($k,$v) = each %foo){
    print "k($k)v($v)", scalar keys %foo, "\n";
}
__END__
k(1)v(2)
k(3)v(4)
k(7)v(8)
k(9)v(10)
k(5)v(6)
k(1)v(2)5
k(1)v(2)5
k(1)v(2)5
k(1)v(2)5
k(1)v(2)5
k(1)v(2)5
...