C++学习之路--类的构建以及数据转换存储

注意理解下面的代码，数据的处理与转换。

头文件：

#ifndef STACK_H
#define STACK_H

class Stack
{
    struct Link
    {
        void* data;
        Link* next;
        Link(void* dat, Link* nxt);
        ~Link();
    }* head;
public:
    Stack();
    ~Stack();
    void push(void *dat);
    void* peek();
    void* pop();
};

#endif

实现文件：

#include "Stack.h"

Stack::Link::Link(void* dat, Link* nxt)
{
    data = dat;
    next = nxt;
}

Stack::Link::~Link(){}

Stack::Stack()
{
    head = 0;
}

void Stack::push(void *dat)
{
    head = new Link(dat, head);
}

void* Stack::pop()
{
    if (head == 0)
        return 0;
    void* result = head->data;
    Link* oldHead = head;
    head = head->next;
    delete oldHead;
    return result;
}

Stack::~Stack(){}

测试文件：

#include <iostream>
#include "Stack.h"
#include <cstdlib>
#include <cassert>
#include <string>
#include <fstream>
using namespace std;

int main()
{
    ifstream in("aa.txt");
    Stack textlines;
    string line;
    while (getline(in, line))
        textlines.push(new string(line));
    string* s;
    while ((s = (string*)textlines.pop()) != 0)
    {
        cout << *s << endl;
        delete s;
    }
    system("pause");
}