C++ Programming: chapter 3 - class 2018, Spring Pusan National University Ki-Joune Li http://lik.pnu.kr

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)

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

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; }

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

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; ?

#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 ?

? #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; ?

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 ?

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

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”);

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”);

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(); }

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(); }

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(); }

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?

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?

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??

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; }