C++ Final Exam Cheat Sheet

So last minute my computer science professor decides to email the class. That we are allowed to bring in a one sided cheat sheet. So seeing as my this is my final exam and is worth 42% of my mark in the class. I decided it might be a good idea to create such a sheet full of info for ease. Last time i heard the exam would only have C++ on it and will deal with mostly classes. So i took a look at all my "class" notes and came up with this cheat sheet/program that goes through everything i learned on classes this semester.

The program i created was rewritten extremely compressed and ugly to save space for future material i decide to put on it. At the moment though here is my cheat sheet.

Source Code
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#include <iostream>
using namespace std;

class study
{
public:
    study(){x = 0,y = 0; n++;}
    study(int a, int b);
    void print(void);
    void displayN(void)const;
    friend study change(study obj){ cin>>obj.x; cin>>obj.y; return obj;}
    friend int area(study);
    study& operator+(study);
    study& setX5(void){this->x = 5; return *this;}
    study& sety10(void){this->y = 10; return *this;}
    friend ostream& operator<<(ostream &output, study &obj){output<<"("<<obj.x<<","<<obj.y<<")"<<endl; return output;}//stream overloading friend
    ~study(){x = 0; y=0; if(n!=0){cout<<"Object deconstruction"<<" Objects remaining = "<<n--<<endl;}}
private://methods in here called utility function
    static int n;
    int x;
    int y;
};
int study::n = 0;

void study::print(void){cout<<x<<endl; cout<<y<<endl;}
void study::displayN(void)const{cout<<"The number of objects created is: "<<n<<endl;}
study::study(int a, int b){ n++; x = a; y = b;}

int area(study obj){ return obj.x*obj.y;}

study& study::operator+(study obj2){this->x = this->x + obj2.x; this->y = this->y + obj2.y; return *this;}

int main()
{
    study obj1;//x = 0 , y = 0
    study obj2(2,4);//x = 2 , y = 4
    const study obj3(5,4);
    study *obj4 = new study(5,5);
    obj1.print();//output: 0  endl 0
    obj2.print();//output: 2  endl 4
    cout<<"The area of obj2: "<<area(obj2)<<endl;//object from area function gets deconstructed
    obj1 = change(obj1);//x = 6 , y = 5
    obj1 = obj1.operator+(obj2);
    obj1.print();// 8, 9
    obj1 = obj1 + obj2;
    obj1.print();//10,13
    obj1.displayN();//3
    //obj3.print(); won't work because const objs can only use const methods
    obj1.setX5().sety10();//cascading member list
    obj1.print();
    cout<<obj1<<endl;//use of operator overloading of <<. Method has to be a friend. ostream for output. istream for input.
    delete obj4;
    return 0;
}

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As you can see it is pretty ugly, but should really benefit me in terms of knowing the syntax of certain programing styles/commands.