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Iterator模式用来解决对一个聚合对象的遍历问题。

Aggregate.h

//Aggregate.h#ifndef _AGGREGATE_H_#define _AGGREGATE_H_class Iterator;typedef int Object;class Interator;class Aggregate{public:	virtual ~Aggregate();	virtual Iterator* CreateIterator() = 0;	virtual Object GetItem(int idx) = 0;	virtual int GetSize() = 0;protected:	Aggregate();private:};class ConcreteAggregate:public Aggregate{public:	enum {SIZE = 3};	ConcreteAggregate();	~ConcreteAggregate();	Iterator* CreateIterator();	Object GetItem(int idx);	int GetSize();protected:private:	Object _objs[SIZE];};#endif //~_AGGREGATE_H_

//Aggregate.cpp#include "Aggregate.h"#include "Iterator.h"#include 
   
    using namespace std;Aggregate::Aggregate(){}Aggregate::~Aggregate(){}ConcreteAggregate::ConcreteAggregate(){	for (int i = 0; i < SIZE; i++)		_objs[i]= i;}ConcreteAggregate::~ConcreteAggregate(){}Iterator* ConcreteAggregate::CreateIterator(){	return new ConcreteIterator(this);}Object ConcreteAggregate::GetItem(int idx){	if (idx < this->GetSize())		return _objs[idx];	else		return -1;}int ConcreteAggregate::GetSize(){	return SIZE;}
   

//Iterator.h#ifndef _ITERATOR_H_#define _ITERATOR_H_class Aggregate;typedef int Object;class Iterator{public:	virtual ~Iterator();	virtual void First() = 0;	virtual void Next() = 0;	virtual bool IsDone() = 0;	virtual Object CurrentItem() = 0;protected:	Iterator();private:};class ConcreteIterator:public Iterator{public:	ConcreteIterator(Aggregate* ag , int idx = 0);	~ConcreteIterator();	void First();	void Next();	bool IsDone();	Object CurrentItem();protected:private:	Aggregate* _ag;	int _idx;};#endif //~_ITERATOR_H_

//Iterator.cpp#include "Iterator.h"#include "Aggregate.h"#include 
   
    using namespace std;Iterator::Iterator(){}Iterator::~Iterator(){}ConcreteIterator::ConcreteIterator(Aggregate* ag , int idx){	this->_ag = ag;	this->_idx= idx;}ConcreteIterator::~ConcreteIterator(){}Object ConcreteIterator::CurrentItem(){	return _ag->GetItem(_idx);}void ConcreteIterator::First(){	_idx = 0;}void ConcreteIterator::Next(){	if (_idx < _ag->GetSize())		_idx++;}bool ConcreteIterator::IsDone(){	return (_idx == _ag->GetSize());}
   

#include "Aggregate.h"#include "Iterator.h"#include 
   
    using namespace std;int main(){	Aggregate* ag = new ConcreteAggregate();	Iterator* it = new ConcreteIterator(ag);	for (; !(it->IsDone()) ; it->Next())	{		cout<
    
     CurrentItem()<
    
   

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