astack.h

对堆栈进行了底层实现

//AStack.h 2008 3 27

template <class Elem>
class AStack
{
private:
	int size;
	Elem* arrayStack;
	int fence;

public:
	AStack(int sz = 100)
	{
		size = sz;
		arrayStack = new Elem[size];
		fence = 0;
	}

	~AStack()
	{
		delete [] arrayStack;
		fence = 0;
	}

	void Clear()
	{
		fence = 0;
	}

	bool Empty()const
	{
		if(fence == 0)
			return true;
		else
			return false;
	}
	
	bool Push(const Elem& a)
	{
		if(fence == size)
		{
			cerr << "Error:The stack is full,you can not push!" << endl;
			return false;
		}
		arrayStack[fence++] = a;
		return true;
	}

	int Size()const
	{
		//查看栈中的元素的个数
		return fence;
	}

	Elem Top()const
	{
		if(fence == 0)
		{
			cerr << "Error:The stack is empty,so you can not ancess the top value!" << endl;
			//强制返回一个Elem类型的0值
			return (Elem)0;
		}
		//attention
		return arrayStack[fence - 1];
	}

	bool Top(Elem& a)const
	{
		if(fence == 0)
			return false;
		a = arrayStack[fence];
		return true;
	}

	bool Pop()
	{
		if(fence == 0)
		{
			cerr << "Error:there is nothing in stack,pop nothing!" << endl;
			return false;
		}
		fence--;
		return true;
	}

	bool PPop(Elem& a)
	{
		if(fence == 0)
			return false;
		a = Top();
		Pop();
		return true;
	}
};