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Hi!

This code is ok:

template<class T>
struct Container
{
T x;
typedef int size_type;
size_type size() { return sizeof T; }
};

Why the compiler (VC7) does not compile the following code?

template<class T>
struct Container
{
T x;
typedef int size_type;
size_type size() const;
};

template<class T>
Container<T>::size_type Container<T>::size() { return sizeof T; }

---

Thanks

Dmytro

Dmytro wrote:
> Hi!
>
> This code is ok:
>
> template<class T>
> struct Container
> {
> T x;
> typedef int size_type;
> size_type size() { return sizeof T; }
> };
>
> Why the compiler (VC7) does not compile the following code?
>
> template<class T>
> struct Container
> {
> T x;
> typedef int size_type;

Why use int for a size_type? Does a negative size make sense?

> size_type size() const;
> };
>
> template<class T>
> Container<T>::size_type Container<T>::size() { return sizeof T; }
>
You left out two important things:

typename Container<T>::size_type Container<T>::size() const {
return sizeof T; }

The typename is required to tell the compiler that
Container<T>::size_type is a type and the const because the prototype
function is const.

--
Ian Collins.

Dmytro <> wrote:

> Why the compiler (VC7) does not compile the following code?
>
> template<class T>
> struct Container
> {
> T x;
> typedef int size_type;
> size_type size() const;
> };
>
> template<class T>
> Container<T>::size_type Container<T>::size() { return sizeof T; }

Where (which line in the above snippet) and which error do you get?
My guess is you're missing a 'typename' in the last line.

hth
--
jb

(reply address in rot13, unscramble first)

Ian Collins wrote:

> Dmytro wrote:
>> Hi!
>>
>> This code is ok:
>>
>> template<class T>
>> struct Container
>> {
>> T x;
>> typedef int size_type;
>> size_type size() { return sizeof T; }
>> };
>>
>> Why the compiler (VC7) does not compile the following code?
>>
>> template<class T>
>> struct Container
>> {
>> T x;
>> typedef int size_type;
>
> Why use int for a size_type? Does a negative size make sense?

Actually, it does. If you want to be able to get an offset between two
arbitrary elements, that offset must be a signed type and will only be able
to span half of the range of the unsigned size type. So the size couldn't
be more anyway. And then, it's always a bad idea to mix signed and
unsigned, so actually, I would prefer a signed size type.

Rolf Magnus posted:

> And then, it's always a bad idea to mix
> signed and unsigned, so actually, I would prefer a signed size type.


Some people simply used "signed int" all the time. The situation is very
similar to how some people will always use "i++" and have no intention of
changing their style.

I myself only use signed integer types when I have to. Elsewhere, I use
unsigned integer types.



--

Frederick Gotham