1. C++ Programming: chapter 3 - class
2018, Spring
Pusan National University
Ki-Joune Li

2. black box (hiding the internal details)
- member functions
- interfaces
- methods
Class
black box (hiding the internal details) ?
Object (or Instance)
Object
(or Instance)
Object
(or Instance)

3. Implementation
Interfaces to outside
Internal member functions
Internal member functions
Internal member functions
Member Data (States)
Member Data (States)
Member Data (States)

4. Scope Resolution Operator
#include <iostream>  using namespace std;    class Point {
private:    int X;      int Y;        int Z;         
public: 
void setX(int a); void setY(int b); void setZ(int c);
void printout() { cout<< “(“ << X << “, “<<Y<<“, “<<Z<<“)\n”; }
int volume(); };     int main() {     Point myPoint;     int vol;     myPoint.setX(7); myPoint.setY(16);
myPoint.setZ(21);
  vol = myPoint.volume(); 
myPoint.printout();      cout <<  vol;     return 0;  }
Class Definition
Object
Scope Resolution Operator
int Point::volume() {
int result;
result=X*Y*Z;
return result; }

5. Private: Encapsulation을 위하여 내부의 내용을 감춤
Private versus Public
Private: Encapsulation을 위하여 내부의 내용을 감춤
Class의 내부에서만 사용가능
Scope resolution operation
Friend
Inheritance
Public
Class의 외부에서 누구나 사용가능 – struct와 유사
주로 외부에 노출되는 interface 함수

6. Function overloading 동일한 이름의 함수를 Parameter 수와 Type으로 Binding ?
#include <iostream>  using namespace std;    class Point {
private:    int X;      int Y;        int Z;         
public: 
void printout() { cout<< “(“ << X << “, “<<Y<<“, “<<Z<<“)\n”; }
void setValues() {X=Y=Z=0;}
void setValues(int a);
void setValues(float a);
void setValues(int a, int b, int c);
}; 
int main() {     Point  myPoint;     float y=10.0; myPoint.setValues();
myPoint.setValues(y);
myPoint.printout();       return 0;  }
int Point::setValues(int m) {
X=Y=Z=m; }
int Point ::setValues(float x) {
X=Y=Z=static_case<int>(x);
int Point ::setValues(int a, int b, int c) {
X=a; Y=b; Z=c; ?

7. #include <iostream>  using namespace std;    class  Point  {
private:    int X;      int Y;        int Z;         
public: 
void printout() { cout<< “(“ << X << “, “<<Y<<“, “<<Z<<“)\n”; }
void setValues(int a);
void setValues(float a);
void setValues(int a, int b, int c);
}; 
int main() {      Point  myPoint;   my Point.setValues();
my Point.printout();       return 0;  }
int Point::setValues(int m) {
X=Y=Z=m; }
int Point::setValues(float x) {
X=Y=Z=static_case<int>(x);
int Point::setValues(int a=0, int b=0, int c=0) {
X=a; Y=b; Z=c;
Default values ?

8. ? #include <iostream> using namespace std; class Point {
private:    int X;      int Y;        int Z;         
public: 
void printout() { cout<< “(“ << X << “, “<<Y<<“, “<<Z<<“)\n”; }
void setValues() {X=Y=Z=0;}
void setValues(float a);
void setValues(int a, int b, int c);
}; 
int main() {     Point  myPoint;     int a=10; myPoint.setValues(a);
myPoint.printout();       return 0;  }
int Point::setValues(float x) {
X=Y=Z=static_case<int>(x); }
int Point::setValues(int a, int b, int c) {
X=a; Y=b; Z=c; ?

9. Call-By Reference &을 이용하면 Parameter passing 때 Call-By reference 가능
Cf. call-by value
#include <iostream>  using namespace std;    class  Point  {
private:    int X;      int Y;        int Z;         
public: 
void printout() { cout<< “(“ << X << “, “<<Y<<“, “<<Z<<“)\n”; }
int setVaues(int &);
void setValues(int a, int b, int c);
}; 
int main() {     Point  Point;     int a=10; myPoint.setValues(a);
cout << “a= “ <<a<<endl; myPoint.setValues(30); //??
      return 0;  }
int Point::setValues(int & m) {
X=Y=Z=m++; }
 Call-by reference와 call-by value의 차이는 ?

10. 가장 기본적인 Member Functions
Constructor/Destructor
Set/Get Functions
Operators
Search/Insert/Delete/Update

11. Class Constructor Class Constructor Object Object
#include <iostream>  using namespace std;    class  Point  {
private:    int X;      int Y;        int Z;         
public: 
Point();
Point a, int b, int c);
printValues() { cout << “X=“<<X<<“, Y=“<<Y<<“, Z=“<<Z<<“\n”;}
}; 
int main() {    Point myPoint;  
Point yourPoint(1,2,3);     return 0;  }
Object
Object
Point::Point() {
X=Y=Z=0;
cout << “Construction with default values\n”;
printValues(); }
Point::Point(int a, int b, int c) {
X=a; Y=b; Z=c;
cout << “Construction with parameterized values\n”);

12. new operator Class Constructor Object Object
#include <iostream>  using namespace std;    class  Point  {
private:    int X;      int Y;        int Z;         
public: 
Point();
Point(int a, int b, int c);
printValues() { cout << “X=“<<X<<“, Y=“<<Y<<“, Z=“<<Z<<“\n”;}
}; 
int main() {   Point *myPointPtr=new Point;
Point *yourPointPtr=new Point(1,2,3);
Point *myPoints=new Point[10];     return 0;  }
Object
Object
Point::Point() {
X=Y=Z=0;
cout << “Construction with default values\n”;
printValues(); }
Point::Point(int a, int b, int c) {
X=a; Y=b; Z=c;
cout << “Construction with parameterized values\n”);

13. Class Destructor Class Constructor Object Destructor
#include <iostream>  using namespace std;    class  Point  {
private:    int X;      int Y;        int Z;         
public: 
Point();
~Point();
Point (int a, int b, int c);
printValues() { cout << “X=“<<X<<“, Y=“<<Y<<“, Z=“<<Z<<“\n”;}
}; 
int main() {    Point myPoint;  
Point yourPoint(1,2,3);  return 0;  }
Constructor
Object
Destructor
Point::~Point() {
cout << “Construction with default values\n”;
printValues(); }

14. delete operator Class Constructor Object Destructor
#include <iostream>  using namespace std;    class  Point  {
private:    int X, Y, Z;         
public: 
Point();
~Point();
Point a, int b, int c);
printValues() { cout << “X=“<<X<<“, Y=“<<Y<<“, Z=“<<Z<<“\n”;}
}; 
int main() {   Point *myPointPtr=new Point;
Point *myPoints=new Point[10];     delete myPointPtr;
delete[] myPoints;’     return 0;  }
Object
Destructor
Point::~Point() {
cout << “Construction with default values\n”;
printValues(); }

15. Copy Constructor Class Constructor Object Object
#include <iostream>  using namespace std;    class  Point  {
private:    int X, Y, Z;         
public: 
Point();
~Point();
Point(const Point &a);
printValues() { cout << “X=“<<X<<“, Y=“<<Y<<“, Z=“<<Z<<“\n”;}
}; 
int main() {     Point firstPoint(1,2,3);  
Point secondPoint(firstPoint);
Point myPoint(5,6,7);  
functionA(myPoint);     return 0;  }
functionA(Point m) {
m.printValues(); }
Constructor
Object
Object
Point::Point(Point & a) {
X=a.X; Y=a.Y; Z=a.Z;
cout << “Copy Construction\n”;
printValues(); }

16. Copy Constructor 언제 호출되는가?
#include <iostream>  using namespace std;    class Point{
private:    float X; float Y;         
public: 
Point(float a): X(a),Y(a) {};
Point(const Point& a);
printValues() { cout << “(“<<X<<“, “<<Y<<“)\n”; }
friend Point operator+(const Point&a, const Point& b);
}; 
int main() {     Point myPoint(1.0); 
Point yourPoint(2.0);
(myPoint+yourPoint).printValues;
   return 0;  }
Point operator+(const Point& a, const Point& b) {
Point temp;
temp.X=a.X+b.X; temp.Y=a.Y+b.Y;
return temp; }
Point::Point(const Point & a) {
X=a.X; Y=a.Y;
cout << “Copy Construction\n”;
printValues(); }
언제 호출되는가?

17. Const return object 를 reference로 하면 어떻게 되는가?
#include <iostream>  using namespace std;    class Point{
private:    float X; float Y;         
public: 
Point(float a): X(a),Y(a) {};
Point(const Point& a);
void printValues() const;
friend Point operator+(const Point&a, const Point& b);
}; 
int main() {     Point myPoint(1.0); 
Point yourPoint(2.0);
(myPoint+yourPoint).printValues;
   return 0;  }
Point operator+(const Point& a, const Point& b) {
Point temp;
temp.X=a.X+b.X; temp.Y=a.Y+b.Y;
return temp; }
void printValues() const { cout << “(“<<X<<“, “<<Y<<“)\n”; }
Point &operator+(const Point& a, const Point& b) {
Point temp;
temp.X=a.X+b.X; temp.Y=a.Y+b.Y;
return temp; }
return object 를 reference로 하면 어떻게 되는가?

18. Constructor와 type casting
Dollar operator+(const Dollar& a, const Dollar& b) {
Dollar temp;
temp.dollarPart=a.dollarPart+b.dollarPart;
temp.centPart=a.centPart+b.centPart;
return temp; }
#include <iostream>  using namespace std;    class Dollar{
private:    int dollarPart; int centPart;         
public: 
Point(float a){dollarPart=a; centPart=a/100;}
Point(int a):dollarPart(a),centPart(0){}
Point(int a,int b):dollarPart(a),centPart(b){}
friend Dollar operator+(const Dollar& a, const Dollar& b);
printValues(){ cout<<“$”<<dollarPart<<“.”<<centPart<<endl;
}; 
int main() {     Dollar myMoney(1.50); Dollar yourMoney(3,20);
(myMoney+yourMoney).printValues();
(myMoney+20).printValues();
(yourMoney+10.50).printValues();
  return 0;  }
+로 정의되지 않았는데??

19. static member, static member fuction
#include <iostream>  using namespace std;    class Point{
private:    float X; float Y; 
static int count;      
public: 
Point(float a): X(a),Y(a) {++count};
Point(const Point& a);
static void printCount();
printValues() { cout << “(“<<X<<“, “<<Y<<“)\n”; }
friend Point operator+(const Point&a, const Point& b);
}; 
int Point::count=0;
int main() {     Point myPoint(1.0); 
Point yourPoint(2.0);
(myPoint+yourPoint).printValues();
Point::printCount();
  return 0;  }
void Point::printCount()
{ cout << “Count=“<<count<<endl; }
Point operator+(const Point& a, const Point& b) {
Point temp;
temp.X=a.X+b.X; temp.Y=a.Y+b.Y;
return temp; }
Point::Point(const Point & a) {
X=a.X; Y=a.Y;
++count; }