'int' is enough for 'length' to migrate code from x86 to x64

[FrankLike via Digitalmars-d]

> If I have two pencils of length 10 cm and 15 cm, then the first 
> one is -5 cm longer than the other.
>
> Of course any physical pencil is always of positive length, but 
> that doesn't mean that typeof(pencil.length) can never be 
> negative.

Right.
'int' is easy to use,is enough,and easy to migrate code to 64 bit.