简单栈的实现

programming

/*
Filename: stack.h
Function: Implemention of stack that can compatible with some 
basic data types like int,char even some custom class
Details: 
*/
#include <iostream>
#define MAXNUM 10
using namespace std;
template<class Item>
struct StackNode
{
    Item s[MAXNUM];
    StackNode* next;
};
template<class Item>
class MyStack
{
    private:
        StackNode<Item>* head;
        int top;
    public:
        MyStack();
        ~MyStack();
        Item Pop();
        void Push(Item item);
        int IsEmpty();
};
template<class Item>
MyStack<Item>::MyStack()
{
    head=NULL;
    top=0;
}
template<class Item>
MyStack<Item>::~MyStack()
{
    while(NULL != head)
    {
        StackNode<Item>* tmp=head->next;
        delete head;
        head=tmp;
    }
}
template<class Item>
Item MyStack<Item>::Pop()
{
    if(IsEmpty())
    {
        cout<<"stack is empty,cannot pop any more!"<<endl;
        return ((head->s)[top]);
    }
    if(top==-1)
    {
        StackNode<Item>* tmp=head->next;
        delete head;
        head=tmp;
        top=MAXNUM-1;
    }
    return ((head->s)[top--]);
}
template<class Item>
void MyStack<Item>::Push(Item item)
{
    if(head==NULL)
    {
        head=new StackNode<Item>;
        if(head==NULL)
        {
            cout<<"initial stack error----malloc error"<<endl;
            return ;
        }
        top=0;
    }
    top++;
    if(top==MAXNUM)
    {
        StackNode<Item>* NewNode=new StackNode<Item>;
        NewNode->next=head;
        head=NewNode;
        top=0;
    }
    (head->s)[top]=item;
}
template<class Item>
int MyStack<Item>::IsEmpty()
{
    return ((head==NULL)||((head->next==NULL)&&(top==0)));
}