pointer in a class

[wysota]

Your code that depends on class A will compile faster as it will not have to parse vector's header file each time A's header is included. The application will run a bit slower though, as it'll have to allocate the vector at some point.

[mickey]

Your code that depends on class A will compile faster as it will not have to parse vector's header file each time A's header is included.

but I asked how write it (this above doens't compile)

The application will run a bit slower though, as it'll have to allocate the vector at some point.

I guess the cause is around the allocation on the heap...

[Shadowfiend]

I think the forward declaration has to look something like:

template <class T> class vector;

template <class T> class vector;

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[wysota]

I'd say it should be "class vector<float>;". I don't see a reason to use a pointer to a vector in this situation, though... It's just asking for trouble and a necessity to write more code.

[mickey]

I'd say it should be "class vector<float>;". I don't see a reason to use a pointer to a vector in this situation, though... It's just asking for trouble and a necessity to write more code.

class vector<float>;
 
class Shape {
	const std::vector<float>* _sides;

class vector<float>;

class Shape {
	const std::vector<float>* _sides;

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It doesn't compile; compile gets many error on the first line (like as I missed the ";").
I know It's unuseful, but I'd like compile it for study....
thanks.

[Shadowfiend]

Probably because you didn't put it in a namespace. Try:

namespace std { class vector<float>; }

namespace std { class vector<float>; }

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or:

namespace std { template <class T> vector; }

namespace std { template <class T> vector; }

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[mickey]

nothing to do

[wysota]

IMHO the pointer shouldn't be const.

[mickey]

IMHO the pointer shouldn't be const.

nothing to do again....

[wysota]

What do you mean by "nothing to do"?

[mickey]

What do you mean by "nothing to do"?

Sorry, my english is not correct.....It means that compiler gets the same errors (a lot) on the line "class vector<float>;" (I took off "const" as you suggested) . Of course, if I include vector.h, there aren't problems...I don't understand how to do this forward declaration

[Shadowfiend]

Sorry, I made a mistake in my template declaration. Try:

namespace std { template <class T> class vector; }

namespace std { template <class T> class vector; }

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That compiles fine on my computer.