find the answer

test.cpp

@@ -0,0 +1,173 @@
+#include <iostream>
+#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) {
+            return true;
+        }
+        return false;
+    }
+
+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) {
+            return true;
+        }
+        return false;
+    }
+};
+
+AbstractUser* current_user = nullptr;
+AbstractUser* users[100];
+int user_cnt = 0;
+
+void print() {
+    if (!current_user) return;
+    for (int i = 0; i < user_cnt; i++) {
+        if (users[i] != current_user && current_user->hasAccessToSee(users[i])) {
+            users[i]->displayRole();
+        }
+    }
+}
+
+void addStudent(string username, string password, int grade) {
+    int index = myfind(users, users + user_cnt, [&](AbstractUser* u) {
+        return u->getUsername() == username;
+    });
+    if (index != -1) {
+        cout << "User already exists!" << endl;
+        return;
+    }
+    if (dynamic_cast<Admin*>(current_user) == nullptr) {
+        cout << "permission denied" << endl;
+        return;
+    }
+    Student* st = new Student(username, password, grade);
+    users[user_cnt++] = st;
+}
+
+int main() {
+    Student* s = new Student("erfan", "pass1", 12);
+    Student* s2 = new Student("rasool", "pass2", 12);
+    Staff* st1 = new Staff("alireza", "staffpass", 1000);
+    Staff* st2 = new Staff("kiyan", "staffpass", 1000);
+    Admin* a = new Admin("yalda", "adminpass", 1200);
+
+    users[0] = s;
+    users[1] = s2;
+    users[2] = st1;
+    users[3] = st2;
+    users[4] = a;
+    user_cnt = 5;
+
+    while (1) {
+        string username, password;
+        cout << "username: ";
+        cin >> username;
+        cout << "password: ";
+        cin >> password;
+
+        int index = myfind(users, users + user_cnt, [&](AbstractUser* u) {
+            return u->getUsername() == username && u->isPasswordCorrect(password);
+        });
+
+        if (index != -1) {
+            current_user = users[index];
+            break;
+        } else {
+            cout << "Login failed. Try again.\n";
+        }
+    }
+
+    int choice;
+    while (1) {
+        cout << "\n1. Print Users\n";
+        cout << "2. Add Student\n";
+        cout << "Enter choice: ";
+        cin >> choice;
+
+        if (choice == 1) {
+            print();
+        } else if (choice == 2) {
+            string user, pass;
+            int grade;
+            cout << "Enter username, password, grade:\n";
+            cin >> user >> pass >> grade;
+            addStudent(user, pass, grade);
+        }
+    }
+
+}