请大家帮忙修改一下这个程序 使用输入输出流将数据写入文件，使得在以后每次启动程序后不必重新输入数据，程序设计马上到时间了，麻烦大家快点帮忙改改，本人将不胜感激！麻烦各位大家了

#include<iostream>
#include<string>
#include<fstream>
using namespace std;
class Base
{
protected:
    int id;//本科生,研究生识别
    int num;
    char name[20];
    char sex[5];
    double ch,en,ma;//成绩
    int birth;

public:
    Base();
    virtual int getid()=0;//本科生,研究生识别
    virtual void set()=0;//纯虚函数，在派生类中调用
    virtual void display()=0;
    double getsum();//取总成绩
    char * getsex();//取性别
    double getch();//取各科成绩
    double geten();
    double getma();
    int getbirth();
    int getnum();//取学号
    char* getname();//取姓名
};


Base::Base()//基类构造
{
    num=0;
    ch=0;en=0;ma=0;
    birth=1900;
}

int Base::getbirth()
{return birth;}

double Base::getsum()
{return ch+en+ma;}

double Base::getch()
{return ch;}

double Base::geten()
{return en;}

double Base::getma()
{return ma;}

int Base::getnum()
{return num;}

char *Base::getsex()
{return sex;}

char * Base::getname()
{return name;}
class College:public Base//本科生类
{
private:
    int id;//本科生识别
    char subject[20];//专业
public:
    College();//College构造
    int getid();//本科生识别
    char* getsub();
    void set();
    void display();
    friend ostream& operator<<(ostream&,const College&);
    friend istream& operator>>(istream&,College&);
};
void College::set()
{
     cout<<"输入本科生信息\n"<<"学号      姓名     性别(man/woman)    专业     三科成绩     出生年\n";
     cin>>num>>name>>sex>>subject>>ch>>en>>ma>>birth;
}

College::College():Base()//College构造
{
    id=0;
}

char*College::getsub()
{return subject;}

int College::getid()
{return id;}

void College::display()//打印
{
    cout<<"\n本科生：\n"<<num<<"      "<<name<<"      "<<sex<<"      "<<subject<<"      "<<(ch+en+ma)/3<<"      "<<(2011-birth)<<endl;
}

//本科生类中重载输入输出符
ostream& operator<<(ostream& out,const College& right)
{

 out<<right.num<<"      "<<right.name<<"      "<<right.sex<<"      "<<right.subject<<"      "<<(right.ch+right.en+right.ma)/3<<"      "<<(2011-right.birth)<<endl;
 return out;
}

istream& operator>>(istream& in,College& right)
{

    in>>right.num>>right.name>>right.sex>>right.subject>>right.ch>>right.en>>right.ma>>right.birth;
    return in;
}
 //研究生类     

class Graduate:public Base
{
private:
    int id;//研究生识别
    char instruct[20];//导师
public:
    Graduate();//Graduate构造
    int getid();
    void set();
    void display();
    char*getins();
    friend ostream& operator<<(ostream&,const Graduate&);
    friend istream& operator>>(istream&,Graduate&);
};

  void Graduate::set()
{
     cout<<"输入研究生信息\n"<<"学号      姓名     性别(man/woman)     导师     三科成绩     出生年\n";
     cin>>num>>name>>sex>>instruct>>ch>>en>>ma>>birth;
}

int Graduate::getid()
{return id;}

char*Graduate::getins()
{return instruct;}

Graduate::Graduate():Base()
{
    id=1;
}

void Graduate::display()
{
    cout<<"\n研究生：\n"<<num<<"      "<<name<<"      "<<sex<<"      "<<instruct<<"      "<<(ch+en+ma)/3<<"      "<<(2011-birth)<<endl;
}
//研究生类中重载输入输出符
ostream& operator<<(ostream& out,const Graduate& right)
{
 out<<right.num<<"      "<<right.name<<"      "<<right.sex<<"      "<<right.instruct<<"      "<<(right.ch+right.en+right.ma)/3<<"      "<<(2011-right.birth)<<endl;
 return out;
}

istream& operator>>(istream& in,Graduate& right)
{
 in>>right.num>>right.name>>right.sex>>right.instruct>>right.ch>>right.en>>right.ma>>right.birth;
 return in;
}
       //主函数 
int main()
{
    int getin,j;//主菜单中接受选择
    int c1,c2,c3,c4,c5,c6,c7,c8;//case中用来接收选择
    Base * p[100];
    int hao[100],htp;// case 8
    int m,n;//case 8
    double zong[100],ztp;//case 8
    static int i=0;//静态，用来统计对象创建的个数

    ofstream out("com.txt");
    ifstream in("com.txt");

lab2:system("cls");
    cout<<"\n\n\n";
    cout<<"                  *----------学生信息管理系统----------*\n\n";
    cout<<"                              1.录入信息\n";
    cout<<"                              2.显示全部学生\n";
    cout<<"                              3.计算平均成绩\n";
    cout<<"                              4.删除一个学生\n";
    cout<<"                              5.按年级输出学生信息\n";
    cout<<"                              6.按性别输出学生信息\n";
    cout<<"                              7.按姓名检索学生\n";
    cout<<"                              8.按总分排序\n";
    cout<<"                              9.结束程序运行\n\n";
    cout<<"输入您的选择(1~8):";
    cin>>getin;

    switch(getin)
    {
    case 1://录入信息

lab1:    system("cls");
        cout<<"1.录入本科生信息"<<endl;
        cout<<"2.录入研究生信息"<<endl;
        cout<<"3.保存所有信息"<<endl;
        cout<<"4.返回上一级菜单"<<endl;
        cout<<"选择:";
        cin>>c1;
        cout<<endl;
        switch(c1)
        {

        case 1:{
                 p[i]=new College;
                 p[i]->set();
                 i++;
                 goto lab1;
               }

        case 2:{
                 p[i]=new Graduate;
                 p[i]->set();
                 i++;
                 goto lab1;
               }
        case 3://输出文件

                 for(j=0;j<i;j++)
                 {
                     if(p[j]->getid()==1)
                        out<<p[j]->getnum()<<" "<<p[j]->getname()<<" "<<p[j]->getsex()<<" "<<p[j]->getch()<<" "<<p[j]->geten()<<" "<<p[j]->getma()<<" "<<2011-p[j]->getbirth()<<endl;
                     if(p[j]->getid()==0)
                        out<<p[j]->getnum()<<" "<<p[j]->getname()<<" "<<p[j]->getsex()<<" "<<p[j]->getch()<<" "<<p[j]->geten()<<" "<<p[j]->getma()<<" "<<2011-p[j]->getbirth()<<endl;
                 }
                 cout<<"          保存成功！";
                 goto lab1;


           default:
               goto lab2;
        }
        break;

    case 2: //显示全部信息
        system("cls");
        cout<<"学生信息\n"<<"学号      姓名     性别(man/woman)     专业/导师     平均成绩     年龄\n";
        for(j=0;j<i;j++)
            p[j]->display();
            cout<<"\n\n输入任意数字返回主菜单：";
        cin>>c2;
        switch(c2)
        {
        case 1:case 2:case 3:default: goto lab2;
        }
    case 3://计算平均成绩
        system("cls");
        cout<<endl<<endl;
        cout<<"                    ------计算平均成绩-----\n";
        cout<<"                       1. 语文平均成绩\n";
        cout<<"                       2. 英语平均成绩\n";
        cout<<"                       3. 数学平均成绩\n";
        cout<<"                    -----------------------\n";
        cout<<"         你的选择：";
        cin>>c3;
        switch(c3)
        {
        case 1:{

                 double sumy=0;
                 for(j=0;j<i;j++)
                 {
                    sumy=sumy+p[j]->getch();
                 }
                 cout<<"\n语文平均成绩:"<<(sumy/i)<<endl;
                 break;
               }
        case 2:{
                 double sume=0;
                 for(j=0;j<i;j++)
                 {
                    sume=sume+p[j]->getch();
                 }
                 cout<<"\n英语平均成绩:"<<(sume/i)<<endl;
                 break;
               }
        case 3:{
                  double summ=0;
                  for(j=0;j<i;j++)
                  {
                    summ=summ+p[j]->getch();
                  }
                  cout<<"\n数学平均成绩:"<<(summ/i)<<endl;
                  break;
               }
        default :
            goto lab2;
        }
        cout<<"\n\n输入任意数字返回主菜单：";
        cin>>c3;
        switch(c3)
        {
        case 1:case 2:case 3:default: goto lab2;

        }

    case 4://删除一个学生
               system("cls");
               cout<<endl<<endl;
               cout<<"                    ------删除一个学生-----\n";
               cout<<"                        1. 按学号删除\n";
               cout<<"                        2. 按姓名删除\n";
               cout<<"                        3. 返回上级\n";
               cout<<"                    -----------------------\n";
               cout<<"         你的选择：";
               cin>>c4;
               switch(c4)
               {
               case 1:
                         int xuehao;
                         cout<<"输入学生的学号:";
                         cin>>xuehao;
                         for(j=0;j<i;j++)
                         {
                             if(p[j]->getnum()==xuehao)
                             {
                                 for(int del=j;del<i;del++)
                                     p[del]=p[del+1];
                                 i--;
                             }
                         }
                cout<<" \n成功删除.......!\n";
                cout<<"\n\n输入任意数字返回主菜单：";
                cin>>c3;
                switch(c3)
                {
                  case 1:case 2:case 3:default: goto lab2;

                }

               case 2:
                         char ming[20];
                         cout<<"输入学生的姓名:";
                         cin>>ming;
                         for(j=0;j<i;j++)
                         {
                             if(p[j]->getname()==ming)
                             {
                                 for(int del=j;del<i;del++)
                                     p[del]=p[del+1];
                                 i--;
                             }
                         }
                cout<<" \n成功删除........!\n";
                cout<<"\n\n输入任意数字返回主菜单：";
                cin>>c3;
                switch(c3)
                {
                  case 1:case 2:case 3:default: goto lab2;

                }
               default:goto lab2;
               }