程序功能部分有问题，目前3，4，5功能有问题，希望可以修改一下

问题遇到的现象和发生背景

程序功能部分有问题，目前3，4，5功能有问题，希望可以帮忙修改一下

遇到的现象和发生背景，请写出第一个错误信息

用代码块功能插入代码，请勿粘贴截图。 不用代码块回答率下降 50%

#pragma once
#include
#include
#include
using namespace std;
class Student
{
private:
 Student* next;
 int student_ID;
 string  name;
 string gender;
 int age;
 string tel;
 string major;
 int flag;
 Student* first;
public:
 Student();
 void read( );//读取学生信息
 void show_Menu();//展示菜单
 void Exitsystem();//退出系统
 void find( );//查找学生信息
 int s_num;//记录学生人数
 void searchbyname( );
 void searchbyID( );
 void searchbytel( );
 void Delete( );
 static int num_total;
 static int num_sex;
 static int num_age;
 Student** s_stuArray;
 ~Student();
 void Add_stu( );
 friend void write(Student stu[], int n);
 void save( );
 void change( );

};
Student::Student()
{
 this->s_num = 0;
 this->s_stuArray = NULL;
 student_ID = 0;
 age = 5;
}
void Student::show_Menu()//目录
{
 cout << "**************************************" << endl;
 cout << "*******欢迎使用学生信息管理系统！*****" << endl;
 cout << "**********0、录入学生信息*************" << endl;
 cout << "**********1、显示学生信息*************" << endl;
 cout << "**********2、查找学生信息*************" << endl;
 cout << "**********3、删除学生信息*************" << endl;
 cout << "**********4、添加学生信息*************" << endl;
 cout << "**********5、修改学生信息*************" << endl;
 cout << "**********6、退出系统*****************" << endl;
 cout << "**************************************" << endl;
 cout << endl;
}
void Student::Exitsystem()
{
 cout << "欢迎下次使用" << endl;
 exit(0);//退出程序
}
void Student::read( )//读取学生信息
{
 ifstream infile;
 infile.open("student.txt", ios::in);
 if (!infile.is_open())
 {
  cout << "open error" << endl;
  return;
 }
 char buf[1024] = { 0 };
 while (infile >> buf)
 {
  cout << buf << endl; 
 }
 infile.close();
}
void Student::find( )
{
 Student* p = NULL;
 int m = 0;
 int flag = 0;
 cout << "\n\t\t******************************\n";
 cout << "\t\t*****1.按学生姓名查找*********\n";
 cout << "\t\t*****2.按学生学号查找*********\n";
 cout << "\t\t*****3.按学生电话号码查找*****\n";
 cout << "请输入你的选择" << endl;
 cin >> m;
 
 switch (m)
 {
 case 1:
  searchbyname();
  break;
 case 2:
  searchbyID();
  break;
 case 3:
  searchbytel();
  break;

 }
}
void write(Student stu[], int n)//录入学生信息

{
 ofstream outfile("student.txt", ios::out);
 if (!outfile)
 {
  cout << "open error!" << endl;
  exit(1);
 }
 cout << "请输入" << n << "个学生信息" << endl;
 cout << "学号  姓名  性别 年龄  电话号码   专业" << endl;
 for (int i = 0; i < n; i++)
 {

  cin >> stu[i].student_ID >> stu[i].name >> stu[i].gender >> stu[i].age >> stu[i].tel >> stu[i].major;
  outfile << stu[i].student_ID << "  " << stu[i].name << "  " << stu[i].age << "  " << stu[i].tel << "  " << stu[i].major << endl;
 }
 outfile.close();
}
void Student::searchbyname( )
{
 system("cls");
 cout << "请输入要查找的的学生姓名：  ";
 int flag = 0;
 string _name;
 cin >> _name;
 cout <<"输入的姓名："<< _name << " first节点 " << first->num_total << endl;
 Student* p = first->next;
 cout << _name << "  " << p->name << endl;
 
 while (p != NULL)
 {
  if (p->name == _name)
  {
   flag = 1;
   cout << "下面是查找匹配结果" << endl;
   cout << "学号:  " << p->student_ID << "  " << "姓名" << p->name << "  "
    << "性别" << p->gender << "  " << "年龄" << p->age << "  " << "电话号码"
    << p->tel << "  " << "专业" << endl;
  }
  p = p->next;
 }
 if (flag == 0)
 {
  cout << "未找到匹配项。。。" << endl;
 }
 system("cls");
}

void Student::searchbyID( )
{
 system("cls");
 int flag = 0;
 int id;
 cout << "请输入待查找学生的学号： ";
 cin >> id;
 Student* p = first->next;
 while (p != NULL)
 {
  if (p->student_ID == id)
  {
   flag = 1;
   cout << "下面是查找匹配结果" << endl;
   cout << endl;
   cout << "学号:  " << p->student_ID << "  " << "姓名" << p->name << "  "
    << "性别" << p->gender << "  " << "年龄" << p->age << "  " << "电话号码"
    << p->tel << "  " << "专业" << endl;
  }
  p = p->next;
 }
 if (flag == 0)
 {
  cout << "未找到匹配项。。。" << endl;
 }
 cout << endl; cout << endl; cout << endl;
 cout << "按任意键继续" << endl;
 system("cls");
}
void Student::searchbytel( )
{
 system("cls");
 int flag = 0;
 string _tel;
 cout << "请输入待查找学生的电话号码： ";
 cin >> _tel;
 Student* p = first->next;
 while (p != NULL)
 {
  if (p->tel==_tel)
  {
   flag = 1;
   cout << "下面是查找匹配结果" << endl;
   cout << endl;
   cout << "学号:  " << p->student_ID << "  " << "姓名" << p->name << "  "
    << "性别" << p->gender << "  " << "年龄" << p->age << "  " << "电话号码"
    << p->tel << "  " << "专业" << endl;
  }
  p = p->next;
 }
 if (flag == 0)
 {
  cout << "未找到匹配项。。。" << endl;
 }
 cout << endl; cout << endl; cout << endl;
 cout << "按任意键继续" << endl;
 system("cls");
}

void Student::Delete( )
{
 string _name;
 system("cls");
 cout << "请输入需要删除的学生姓名：" << endl;
 cin >> _name;
 int k = 0;
 Student* p = first;
 Student* pre = first;
 while (p->next)
 {
  pre = p->next;
  if (pre->name == _name)
  {
   p->next = pre->next;
   k = 1;
   delete pre;
  }
  p = p->next;
 }
 if (k == 0 && p->name != _name)
  cout << "记录为空！" << endl;
 
}

void Student::Add_stu()
{
 int addNum = 0;
 cout << "请输入添加学生的数量" << endl;
 cin >> addNum;
 if (addNum > 0)
 {
  int newSize = this->s_num + addNum;
  Student** newSpace = new Student * [newSize];
  if (this->s_stuArray != NULL)
  {
   for (int i = 0; i < this->s_num; i++)
   {
    newSpace[i] = this->s_stuArray[i];
   }
  }
  for (int i = 0; i "请输入" << addNum << "个学生信息" << endl;
   cout << "请输入学生的学号  姓名 性别 年龄 电话号码  专业" << endl;
   cin >> student_ID >> name >> gender >> age >> tel >> major;
  }
  delete[]this-> s_stuArray;
  this->s_stuArray = newSpace;
  this->s_num = newSize;
  this->save();//保存数据到文件中
  cout << "成功添加" << addNum << "名学生" << endl;
 }
 else
 {
  cout << "输入数据有误" << endl;
 }
 system("pause");
 system("cls");
}
void Student::save()
{
 ofstream outfile;
 outfile.open("f1.txt", ios::out);
 for (int i = 0; i < this->s_num; i++)
 {
  outfile << this->s_stuArray[i]->student_ID << this->s_stuArray[i]->name << this->s_stuArray[i]->gender <<
   this->s_stuArray[i]->age << this->s_stuArray[i]->tel <<
   this->s_stuArray[i]->major << endl;
 }
 outfile.close();
}
Student::~Student()
{
 if (this->s_stuArray != NULL)
 {
  delete[]s_stuArray;
  this->s_stuArray = NULL;
 }
}
void Student::change()
{
 system("cls");
 int flag = 0, temp;
 int _id, _age,_name1,_gender,_tel,_major;
 string _name;
 cout << "请输入需要改动信息的学生姓名：" << endl;
 cin >> _name;
 Student* p = first->next;
 while (p != NULL)
 {
  if (p->name == _name)
  {
   flag = 1;
   cout << "该学生当前信息如下:" << endl;
   cout << "学号：" << p->student_ID << "姓名:" << p->name << "性别：" << gender << "年龄：" << p->age << "电话号码" << p->tel << "专业" << major << endl;
  }
  cout << "需要修改哪一项" << endl;
  cout << "1.学号" << endl << "2.姓名" << endl << "3.性别" << endl << "4.年龄" << endl << "5.电话号码" << endl << "6.专业" << endl;
  cin >> temp;
  switch (temp)
  {
  case 1:
  {
   cout << "请输入新的学号" << endl;
   cin >> _id;
   p->student_ID = _id;
  }
  break;
  case 2:
  {
   cout << "请输入新的姓名" << endl;
   cin >> _name1;
   p->name = _name;
  }
  case 3:
  {
   cout << "请输入新的性别" << endl;
   cin >> _gender;
   p->gender = _gender;
  }
  break;
  case 4:
  {
   cout << "请输入新的年龄" << endl;
   cin >> _age;
   p->age = _age;
  }
  break;
  case 5:
  {
   cout << "请输入新的电话号码" << endl;
   cin >> _tel;
   p->tel = _tel;
  }
  break;
  case 6:
  {
   cout << "请输入新的专业" << endl;
   cin >> _major;
   p->major = _major;
  }
  break;
  cout << "修改后的信息如下" << endl;
  cout << "学号:  " << p->student_ID << "  " << "姓名" << p->name << "  "
   << "性别" << p->gender << "  " << "年龄" << p->age << "  " << "电话号码"
   << p->tel << "  " << "专业" << endl;
  default:
   cout << "输入有误" << endl;
  }
  p = p->next;
 }
 if (flag == 0)
  cout << "当前记录中没有此学生" << endl;
}

int main()
{
 Student a[2];
 int choice = 0;
 while (true)
 {
  a[2].show_Menu();
  cout << "请输入您的选择" << endl;
  cin >> choice;
  switch (choice)
  {
  case 0: //录入信息
   write(a, 2);
   break;
  case 1:
   a[2].read();//显示学生信息
   break;
  case 2:
   a[2].find();//查询学生信息
   break;
  case 3:
   a[2].Delete();//删除学生信息
   break;
  case 4:
   a[2].Add_stu();//添加学生信息
   break;
  case 5:
   a[2].change();
   break;
  case 6:a[2].Exitsystem();
   break;
  default:
   system("cls");
   break;
  }
 }
 return 0;
}

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