链表的方式实现栈

• 栈的定义：只能在表的一端进行插入和删除元算的线性表，后进先出的规则，凡是在逻辑上需要“后进先出”的操作和过程都能用上栈。一些具体应用有：函数的求值，过程的调用与返回，递归过程的实现
• 栈的基本运算：入栈（插入）、出栈（删除）、置栈空、判断是否为空、取栈顶元素

//stack chain storage structure
#include<iostream>
using namespace std;

class stack_chain;

class node{
public:
    friend class stack_chain;
private:
    char  _data;
    node* _next;
};

class stack_chain{
public:
    stack_chain(){_top=0;}
    ~stack_chain();     //release memory
    bool push(char& c); //push c into stack
    bool pop();  //remove an element from stack
    bool get_top(char& c); //get top element
    void clear();        //clear stack
    void display();
    
private:
    node* _top;
    int   _length;
};

stack_chain::~stack_chain(){
    clear();
}

bool stack_chain::push(char& c){
    node* tmp = new node;
    tmp->_data = c;
    tmp->_next=_top;
    _top= tmp;
    _length++;
    return true;
}

bool stack_chain::pop(){
    if(_top==0) return false;
    node* tmp=_top; 
    _top=tmp->_next;
    delete tmp;
    _length--;
    return true;
}

bool stack_chain::get_top(char& c){
    if(_top==0) return false;
    c=_top->_data;
    return true;
}

void stack_chain::clear(){
    node* tmp;
    while(_top!=0){
        tmp=_top;
        _top=_top->_next;;
        delete tmp;
    }
} 

void stack_chain::display(){
    node* tmp=_top->_next;
    while(tmp!=0){
        cout << tmp->_data;
        tmp= tmp->_next;
    }
    cout << endl;
}

int main(){
    char str[]="stack chain test...";
    stack_chain link;
    for(int i=0; str[i]!=0; i++) link.push(str[i]);
    link.display();
    link.pop();
    char t;
    link.get_top(t);
    cout << t << endl;
    link.clear();
    return 0;
}