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oops : 
class Teacher{
	private:
		string salary; //data hiding using encapsulation
	public:
		//default constructor 
		Teacher(){ 
			dept="cs";
		}
		//parameterized constructor
		Teacher(string n, string d){
			name=n;
			dept=d;
		}
		//copy constructor
		Teacher(Teacher &obj){
			this->name=obj.name;
			this->dept=obj.dept;
		}
		//if we want the parameters to resemble the names of the attributes 
		//this keyword refers object's property
		Teacher(string name, string dept){
			name=name; 
			dept=dept; //very confusing for compiler
			this->name=name;
			this->dept=dept;//left prop is object prop
		}
		string name;
		string dept;
		void changeDept(string newdept){
			dept=newdept;
		}
		//setter and getter methods to access private member variable - salary
		void setSalary(int s){
			salary = s;
		}
		int getSalary(){
			return salary;
		}
		void getinfo(){
			cout<<name<<endl;
			cout<<dept<<endl;
		}
};

//SHALLOW-DEEP COPY EXAMPLE
class Student{
	public:
		string name;
		double* cgpaptr;
		//parameterized constructor
		Student(string n, double cgpa){
			this->name=n;
			cpaptr=new double();
			*(cgpaptr)=cgpa;
		}
		//copy constructor - shallow copy / default copy constructor that will also be created by compiler if we dont create
		Student(Student &obj){
			this->name=obj.name;
			cgpaptr = new double(); //re-allocation of dynamic memory
			*cgpaptr=*(obj.cgpaptr); //value stored not address
		}

		//deep copy - custom copy constructor - mandatory
		Student(Student &obj){
			this->name=obj.name;

			this->cgpaptr=obj.cgpaptr;
		}

		//destructor
		~Student(){
		//delete all dynamically allocated memory
			delete cgpaptr; //avoid memory leak
		}
};

int main(){
	Teacher t1;
	t1.name="x";
	t1.dept="cs"; 
	cout<<t1.salary<<endl; //not accessible as private
	t1.setSalary(200);
	cout<<t1.getSalary()<<endl; //acessible now
	t1.getinfo();

	//default copy constructor 
	Teacher t2(t1); //passing reference of object
	t2.getinfo(); //works absolutely fine

	//custom copy constructor
	Teacher t3(t1);
	t3.getinfo();

	//shallow copy
	Student s2(s1);
	cout<<*(s1.cgpaptr)<<endl; //8.9
	*(s2.cgpaptr)=9.2;
	cout<<*(s1.cgpaptr)<<endl; //9.2
	cout<<*(s2.cgpaptr)<<endl; //9.2
	//we changed s2 but s1 also changed coz pointing to same address - shallow copy

	//deep copy 
	Student s2(s1);
	cout<<*(s1.cgpaptr)<<endl; //8.9
	*(s2.cgpaptr)=9.2;
	cout<<*(s1.cgpaptr)<<endl; //8.9
	cout<<*(s2.cgpaptr)<<endl; //9.2
}