COP 3530
Discussion Session #2
Ferhat Ay
COP3530-Ferhat Ay-Discussion Ses.#2
1/18/2011
1
Few things about me
• My name is difficult!
Fer-hat, Fur-hot, Far-had, Frad, Fred, Frank, or just say F.
•
I’m a PhD student (terrible life choice)
•
Research interests: Bioinformatics, Biological Networks
http://www.cise.ufl.edu/~fay
•
Interests: Soccer, driving …
•
Email me: fay@cise.ufl.edu
•
Facebook page? Some sort of communication?
COP3530-Ferhat Ay-Discussion Ses.#2
1/18/2011
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Why are we here?
•
Inheritance
•
Static Binding - Dynamic binding (Virtual functions)
•
Polymorphism
•
Multiple Inheritance
•
Abstract Classes (Pure Virtual Functions)
• Hints about HW1!!
•
Game time!
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Inheritance
base class, parent class,
superclass
derived class, child class,
subclass
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Derived Class
What a derived class -----can inherit
 All the member data (may not always have the right to access)
 All the member functions (may not always have the right to access)
 The same initial data layout as the base class
cannot inherit
X
Constructors, destructors, assignment operator
can add
+
+
+
New member data
New member functions
New constructors, destructors
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Member Functions
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Constructors, Destructors
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Creation, Deletion
Derived object created:
• Space allocated for the full object (base + derived members)
• Constructor of base class is called to initialize base data members
• Constructor of derived class is called to initialize derived class data members
• Derived class object is good to go
Destroyed (goes out of scope or deleted) :
•
Destructor of derived class is called first
•
Destructor of base class is called next
•
All the allocated space for the object is given back
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Static vs Dynamic Binding
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Virtual Destructor Rule
•
If a class has at least one virtual member function, a virtual destructor
is needed.
•
A virtual destructor causes the compiler to use dynamic binding
when calling the destructor.
class Mario{
…..
public:
…..
virtual ~Mario() {cout<<“Game Over!”<<endl;}
…..
}
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Polymorphism in C++
 Static Polymorphism
• Function/Operator Overloading
• Class/function templates
 Dynamic polymorphism
• Polymorphism through inheritance/Virtual member functions
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Polymorphism-Example
#include <iostream>
class Person {
public:
virtual void print(){std::cout << "a person";}
virtual ~Person() {}
};
class Student: public Person {
public:
void print() {std::cout << "a student";}
};
int main(){
Person* p = new Student; // A generic pointer,
// set to point a Student
p > print(); // "a student “
delete p;
return 0;
}
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Multiple Inheritance -Ambiguity
class W { /* ... */ };
class X : public W { /* ... */ };
class Y : public W { /* ... */ };
class Z : public X, public Y { /* ... */ };
int main () {
Z z;
X* xptr = &z; // valid
Y* yptr = &z; // valid
W* wptr = &z; // error, ambiguous reference to class W
// X's W or Y's W ?
}
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Multiple Inheritance – Non-ambiguous
class W { /* ... */ };
class X : public virtual W { /* ... */ };
class Y : public virtual W { /* ... */ };
class Z : public X, public Y { /* ... */ };
int main () {
Z z;
X* xptr = &z; // valid
Y* yptr = &z; // valid
W* wptr = &z; // valid, W is virtual, only one W exists
}
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Restricted Inheritance
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Casting in Inheritance
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Abstract (Base) Classes
class Shape {
public:
Shape ( Point2d& position, Color& c) : center(position) , color(c) {};
virtual void rotate(double radians) = 0;
virtual bool draw(Screen &) = 0;
virtual ~Shape(void) = 0;
private:
Point2d center;
Color color;
};
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Abstract (Base) Classes
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One more example
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Program 1.11
template <class T>
void make2dArray(T ** &X, int noOfRows, int noOfCols)
{
X = new T* [noOfRows];
for(int i=0; i < noOfRows; i++){
X[i] = new T [noOfCols];
}
}
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Program 1.12
template <class T>
void delete2dArray(T ** &X, int noOfRows)
{
for(int i=0; i < noOfRows; i++){
delete [] X[i];
}
delete []X;
X=NULL;
}
HW1
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References & Resources:
Google
http://ocw.mit.edu/index.htm
http://www.csse.monash.edu.au/~cema/courses/CSE2305/Topics/05.09.Inheritance/html/text.html
http://publib.boulder.ibm.com/infocenter/comphelp/v8v101/index.jsp
http://www.cplusplus.com/doc/tutorial/inheritance/
http://www.compgeom.com/~piyush/teach/3330/slides/L14_Inheritance.pdf
http://cpp.datastructures.net/
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Anyone bored of World of
Warcraft?
loose lose
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