trouble making a [simple] templated node-based stack

nadroj · 02-14-2006, 05:18 PM

ill keep it simple. heres my Stack.h (portion):

Code:

template <class DT>
struct Node
{
	DT data;	
	Node* pUnder;
};

template<class DT>
class Stack
{
private:  // <--- compiler error points here
	Node* pTop;
public:
	Stack();
	~Stack();
	DT pop();
	bool add(DT);
	DT peek();
	void clear();
	int getSize();
};

error in dev C++ is:
- ISO C++ forbids declaration of `Node' with no type
- expected `;' before '*' token

i havent done any templated list-type before.. so im sure its a simple syntax error im doing.

thanks for any help

frob23 · 02-14-2006, 05:28 PM

I'm a C programmer, so c++ may have changed this, but you probably need to change:

Code:

Node* pTop;

to

Code:

struct Node* pTop;

and

Code:

Node* pUnder;

to

Code:

struct Node* PUnder;

That should clear up the errors. It's common to typedef structure pointers to avoid this typing.

Code:

typedef struct Node * NodePtr;

Or something like that... they you could just type:

Code:

NodePtr PUnder;

nadroj · 02-14-2006, 05:34 PM

in the past when i have made other lists (or queue, stack, etc) i didnt have to do what you said. the problem i have is that im making one that is templated, so the data in the node can be anything specified at initial creation of the object (of type Stack)

but, i tried what u did (ie struct Node* pTop) and it now points to the line after the line i said was the error in the 1st post, and says: 'template argument required for `struct Node' '

im almost certain its that im missing a 'template <class DT>' or some variant of that (or have too many!) somewhere.. but iv never made a class like this before so i dont know how it SHOULD be.

thanks

dmail · 02-14-2006, 05:41 PM

Is this just an exercise? if not why not use std::stack which is a template already.
Try something like:

Code:

template <class DT>
struct Node
{
	DT data;	
	Node<DT>* pUnder;
};

template<class DT>
class Stack
{
private:  // <--- compiler error points here
	Node<DT>* pTop;
public:
	Stack();
	~Stack();
	DT pop();
	bool add(DT);
	DT peek();
	void clear();
	int getSize();
};

also are you putting function definitions for the template class in the header file? thats where they need to go.

nadroj · 02-14-2006, 05:52 PM

thanks dmail!

i tried putting the 'Node<DT>*' in afew combinations (from the 2 that u said) and it seems like it only needs to be used in the 2nd one, ie Node<DT>* pTop. the first one (in struct definition) doesnt need it, it seems good as-is.

can u explain why i need to put that in there? i wouldnt have thought ud need to put that there.. oh well.

and yes, this is an exercise so i need to make my own rather than use STL or whatever.

Thanks alot though

edit: oh ya almost forgot... yes i am implementing the methods, i just pasted the main outline of the class file, including function prototypes. i excluded the rest because i said i wanted to keep it simple, because i knew the rest was irrelevant