我在函数返回了一个指针，然后返回指针的内容丢失了，请各位大佬帮忙看看（very thanks）

VC6的编译器，没有警告，然后在运行程序的时候就终止工作。

// 307.cpp : Defines the entry point for the console application.//
//#include "stdafx.h"
#include <stdio.h>
#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
using namespace std;
void Menu();
class account
{
        string user;
        string pass;
public:
        void reg();//注册
        void login();//登录
        void password();
private:
        void save();
        string** read();
};
void account::reg()
{  
    ofstream out ("account.dat", ios::app);
    //string disk[4][2];
    //string ** d1;
    string pass1;
    string pass2;
    cout<<"欢迎来到注册页面"<<endl;
    cout<<"请输入用户名"<<endl;   
    cin>>user;
    cout<<"请输入密码"<<endl;
    cin>>pass1;
    cout<<"请再输入一次密码"<<endl;
    cin>>pass2;
    string **disk=read();
    for ( int i = 0 ; i <sizeof(disk[0]); i++)
   {
      if(disk[i][0] != user )
      {
             cout<<"ok"<<endl;
             break;
      }
      else
      {   
      
               cout<<"用户名已经存在"<<endl;
               cout<<"请重新注册："<<endl;
               reg();
      }
    }
if(pass1==pass2)
    {
      cout<<"注册成功"<<endl;
      save();
     
    }
    else
    {
       cout<<"输入的密码两次不相同"<<endl;
       reg();
    }
}

void account::login()
{
    //string disk[4][2];
    cout<<"欢迎来到登录界面"<<endl;
    cout<<"请输入您的用户名：";
    cin>>user;
    cout<<"请输入您的密码：";
    cin>>pass;
    cout<<endl;
    string **disk=read();
    for(int i=0;i<sizeof(disk);i++)
    {
        if(disk[i][0]==user&&disk[i][1]==pass)
          {
               cout<<"登录成功！进入下一个菜单"<<endl;
               Menu();
          }
         else
         {
             cout<<"用户名注册错误或者密码错误"<<endl;
             cout<<"请重新登录"<<endl;   
             login();
         }
    }
  
}
string** account::read()
{
    ifstream in("account.dat");
    int x, y;
    string disk[4][2];
    for (x = 0; !in.eof(); x++)
    {
        string line;
        getline(in,line);
        istringstream ss(line);
        for (y = 0; !ss.eof(); y++)
        {
            ss >> disk[x][y];   
        }
    }
    /*string *a ;
    a=&disk;*/
   
   return (string**)disk;
}
void account::save()
{
  ofstream out ("account.dat",ios::out);
  out<<user<<" "<<pass<<endl;
  //out.close();
}
class book
{
  protected:
        string cname;//餐厅名字
        string num;//电话号码
        int month;
        int day;
        int quantity;//人数
        string remark;
  public:
        book(string pcname);
        void enter();
        void report();
};
book::book(string pcname):
cname(pcname)
{}
void book::enter()
{
  cout<<"请输入要预定"+cname+"的相关信息（电话号码、日期、人数、备注）："<<endl;
  cin>>num>>month>>day>>quantity>>remark;
}
void book::report()
{
  cout<<"以下是您预定餐厅的信息"<<endl;
  cout<<"餐厅名字："<<cname<<endl;
  cout<<"您的电话："<<num<<endl;
  cout<<"日期为：  "<<month<<"月"<<day<<"日"<<endl;
  cout<<"人数：    "<<quantity<<endl;
  cout<<"备注：    "<<remark<<endl;
}

int main()
{
 account acc1;
  int choose=-1;
  while(1)
  {
    cout<<"请选择"<<endl;
    cout<<"************************"<<endl;
    cout<<"    0.退出     "<<endl;
    cout<<"    1.注册      "<<endl;
    cout<<"    2.登录      "<<endl;
    cout<<"************************"<<endl;
    cin>>choose;
    switch (choose)
    {
        case 1:    acc1.reg();
                   continue;
        case 2:    acc1.login();
                   continue;
        case 0:    exit(0);      
        default:    cout<<"选择超出范围"<<endl;
        continue;
    }
  }
 
  Menu();
  return 0;
}
void Menu()
{
  while(1)
  {
    book a1("307");
    int choose=-1;
    cout<<"请选择"<<endl;
    cout<<"************************"<<endl;
    cout<<"      0. 退出     "<<endl;
    cout<<"      1.填写预定信息      "<<endl;
    cout<<"      2.您的预定信息      "<<endl;
    cout<<"************************"<<endl;
    cin>>choose;
    switch (choose)
    {
        case 1:    a1.enter();
                    continue;
        case 2:    a1.report();
                    break;
        case 0:    exit(0);      
        default:    cout<<"选择超出范围，请重新选择"<<endl;
                    continue;
    }
  }
}

不用看你的代码, 一看内容丢失就知道你返回的绝对是函数里面的变量
出了函数这个变量就变回收了
声明变量的时候声明为指针然后返回就可以了