Test.cpp

#include <iostream>
 #include <functional> // For std::hash
 #include <string>
 using namespace std;
 const int MAX = 100;
 
 template <typename T, typename F>
 int myfind(T *begin, T *end, F f)
 {
   for (T *itr = begin; itr != end; itr++)
   {
 
     if (f(*itr))
     {
       return itr - begin;
     }
   }
   return -1;
 }
 
 class AbstractUser
 {
 public:
   AbstractUser(const string &username, const string &password)
       : username(username), password(password) {}
 
   virtual ~AbstractUser() = default;
 
   virtual void displayRole() const = 0;
   virtual bool hasAccessToSee(AbstractUser *) const = 0;
 
   string getUsername() const
   {
     return username;
   }
   bool isPasswordCorrect(const string &pass)
   {
     return (pass == password);
   }
 
 protected:
   string username;
   string password;
 };
 
 class Student : public AbstractUser
 {
 public:
   Student(const string &username, const string &password, int grade)
       : AbstractUser(username, password), grade(grade) {}
 
   void displayRole() const override
   {
     cout << "Student: " << username << ", Grade: " << grade << endl;
   }
   bool hasAccessToSee(AbstractUser *user) const override
   {
     return false;
   }
 
 private:
   int grade;
 };
 
 class Staff : public AbstractUser
 {
 public:
   Staff(const string &username, const string &password, int salary)
       : AbstractUser(username, password), salary(salary) {}
 
   void displayRole() const override
   {
     cout << "Staff: " << username << ", Salary: " << salary << endl;
   }
   bool hasAccessToSee(AbstractUser *user) const override
   {
     if (dynamic_cast<Student *>(user) != nullptr)
     { // not the best way
       return true;
     }
   }
 
 private:
   int salary;
 };
 
 class Admin : public Staff
 {
 public:
   Admin(const string &username, const string &password, int salary)
       : Staff(username, password, salary) {}
 
   void displayRole() const override
   {
 
     cout << "Admin ";
     Staff::displayRole();
   }
   bool hasAccessToSee(AbstractUser *user) const override
   {
     if (dynamic_cast<Admin *>(user) == nullptr)
     { // not the best way
       return true;
     }
   }
 };
 
 AbstractUser *current_user;
 AbstractUser *users[100];
 int user_cnt;
 
 void print()
 {
   if (!current_user)
   {
     return;
   }
   for (AbstractUser *user : users)
   {
     if (current_user->hasAccessToSee(user))
     {
       user->displayRole();
     }
   }
 }
 
 void addStudent(string username, string password, int grade)
 {
   int index = myfind(users, users + user_cnt, [=](AbstractUser *u1)
                      { return (u1->getUsername() == username); });
   if (index != -1)
   {
     return;
   }
   if (dynamic_cast<Admin *>(current_user) == nullptr)
   {
     cout << "permision denied" << endl;
     return;
   }
   Student *st = new Student(username, password, grade);
   users[user_cnt++] = st;
 }
 
 int main()
 {
   Student s("st1", "pass1", 12);
   Student s2("st2", "pass2", 12);
   Staff st("staff1", "staffpass", 1000);
   Admin a("admin1", "adminpass", 1000);
   user_cnt = 4;
   users[0] = &s;
   users[1] = &s2;
   users[2] = &st;
   users[3] = &a;
 
   while (1)
   {
     string username, password;
     cout << "username: ";
     cin >> username;
     cout << "password:";
     cin >> password;
     int index = myfind(users, users + user_cnt, [=](AbstractUser *u1)
                        { return (u1->getUsername() == username && u1->isPasswordCorrect(password)); });
     if (index != -1)
     {
       current_user = users[index];
       break;
     }
   }
   int choice;
   while (1)
   {
     cout << "1.print" << endl;
     cout << "2.adduser" << endl;
     cin >> choice;
     if (choice == 1)
     {
       print();
     }
     else
     {
       string user, pass;
       int grade;
       cin >> user >> pass >> grade;
       addStudent(user, pass, grade);
     }
   }
 
   return 0;
 }