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2 Object-Oriented Programming(OOP)./ '%% '%% "%0 1!2 12!22!!22!,!%'32 01 ' ',%%! %%! '2 %./ '%% % The three fundamental attributes of OOP: Encapsulation,% " 7%801% ' "0 12'9 Inheritance New objects are incorporated into an hierarchical object-tree. The new object takes over all data-structures and functions from their parents. Now this new object can be changed by adding new datastructures and/or functions. Polymorphism One function has a unique name within the whole hierarchy. This function is implemented in each object of the hierarchical tree in a different way.

3 Encapsulation Example: Font-manipulation :!" !!"#$%%!"$ struct demo... init(); get(..); rotate(..) print(..);... data code Definition of data-structures and functions are divided. It is possible to manipulate the data without using the predefined functions.!" $%%!"$ class class elementary functions constructor (..) get(..); rotate(..) print(..); Normally the data-structure is a private element and therefore can be manipulated only by functions within the same object. These functions are defined as public and can be used by others. &'()' ** ' % /% ; 1 % ' /! < 1 '%%% / 1

4 Inheritance % %!1! 1 7/8 1! 1 % = 2 %9- %2 1 %% % >?1!0 1 % % moths butterflies flies - 1 7/81'@1!% 4= 7$2!1 >8% 1 0= % %:% % " A8 +,' *)(- + /-,&0( +1 ' & -')*( 0(++2-0-'))(0' BEFORE WRITING ONLY ONE LINE OF CODE USING OOP IT IS VERY IMPORTANT TO DEFINE ALL CLASSES AT ALL LEVELS! B12 ;"C! -B$.-5" #%% " % 8

5 POLYMORPHISM '%% %! = %, %2%' 21..##2%'% 1!2%' %' '%% - 2 " % %'% 12 "%2% 1 7%E;8

6 Example // class Location describes screen locations in X and Y coordinates // class Point describes whether a point is hidden or visible // class Circle describes the radius of a circle enum Bool False, True; A Classe Location is created. class Location protected: int X; int Y; public: outside // allows derived class to access private data // actual X-position // actual Y-position // these functions can be accessed from Location(int InitX, int InitY); int GetX(); int GetY(); // Initialise // returns actual X-Position // returns actual Y-Position ; Now we create a new class POINT based on LOCATION. Therefore Point inherits all data and functions from LOCATION. We only add a new data word VISIBLE which indicates if the point is lighted or not. One important new function is MOVETO which allows the class POINT to move to another place on the $?1 D, C!1! 7#2%'%8-1 %'% $?.D?,. 212.D?,. 1!! $?

7 class Point : public Location //derived from class Location //public derivation means that X and Y are protected within Point protected: Bool Visible; //classes derived from Point will need access to Visible public: Point(int InitX, int InitY); virtual void Show(); virtual void Hide(); Bool IsVisible(); void MoveTo(int NewX, int NewY); // constructor // Show the point on screen // Hide the point // returns actual state (Visible or not) // Move Point to new location ; The class CIRCLE is based on POINT. We add the new data word RADIUS and overwrite the function SHOW and HIDE because a circle must be drawn in a different way. Furthermore we add the new functions EXPAND and CONTRACT to manipulate the circle. Because of the INHERITANCE of OOP, CIRCLE is able to MOVETO another location and to be visible or not class Circle : public Point Location // derived from class Point // and ultimately from class protected: int Radius; // actual value for Radius public: Circle (int InitX, int InitY, int InitRadius); // constructor virtual void Show(); virtual void Hide(); void Expand(int ExpandBy); void Contract(int ContractBy); // Show the Circle on screen // Hide the Circle // Make Circle bigger // Makes Circle smaller ;

8 In the described way more classes can be derived (e.g lines, rectangles etc.) to build a complex object tree. This can be used to build new application (e.g. CAD-Systems or simulation-programs).!-'('3 3-&-+04--*)(-*-''-(++#!"5 /* */ Location::Location(int InitX, int InitY) // The Constructor of LOCATION X=InitX; Y=InitY; // Set init-values int Location::GetX() return (X); // X is accessable in the object int Location::GetY() return (Y); // Y is accessable in the object!-'('3 3-&-+04--*)(-*-''-(++!"5 /* */ Point::Point(int InitX, int InitY) : Location (InitX,InitY) // The Constructor Visible = False; // initially point is not visible

9 + + - *)(-*-'' - 0' 678 ' - 0(++!"!*+ 4- '/-3-'&-/-&0(++-+ void Point::Show() Visible=True; putpixel (X,Y,getcolor()); // Point becomes now visible // draw point *)(-*-'' - 0' 7! ' - 0(++!"!*+ 4- '/-3-'&-/-&0(++-+ void Point::Hide() Visible=False; putpixel (X,Y,getbkcolor()); // Point becomes now invisible // draw point with background color ++-*)(-*-''-0'!6!6!#+90'04-+-& &-/-&0(++-+ Bool Point::IsVisible() return (Visible); // return current state void Circle::Hide()

10 unsigned int TmpColor = getcolor(); // save current color // new color is background // erase circle // draw circle with background- // restore old color setcolor(getbkcolor()); Visible=False; circle (X,Y,Radius); color setcolor(tmpcolor); void Circle::Expand (int ExpandBy) Hide(); Radius +=ExpandBy // erase old circle // new radius if (Radius < 0) Radius = 0; // avoid negative radius Show(); void Circle::Contract(int ContractBy) // Makes Circle smaller Expand (-ContractBy); 7--++')' *+- *-30&--+3'4:-0+2'-'&'- 0(-9+4''4:-0+-+'3!-.+-)0(-+(*'/-'-3 ('0'++&'-4,+ -0'!"5%!"5%0(+ -/( 0'+!# 5678 &!# 57! '&3 0'-0 00( (-+/+4(-&+'3-&-... // Here are some definitions int main ()

11 ... Circle ACircle (10,10,5); // define a Circle at 10/10 with Radius 5 Point APoint (120,110); // and a point at 120/110 ACircle.Show(); APoint.Show(); ACircle.MoveTo (10,30); // show the circle on the screen // show the point on the screen // Move the circle to a new location // CIRCLEW::SHOW and CIRCLE::HIDE are // called when executing Moveto!! APoint.MoveTo (5,5); // Move Point to 5/5 //(POINT::SHOW and POINT::HIDE are used) //But both use POINT::MOVETO if (ACircle.IsVisible()) // if ACircle is visible we hide it. ACircle.Hide();...

12 Constructor and destructor,112! :!! '% int Radius; // define a variable... // other code here Radius = 5; // assign it a value *2 %%2 4 int Radius = 5; // define and initialize to 7 4 %!1 % :! 4 2!! 12 4%%> ;!'%%, '% 0!!""! void, %1% % -!2 02F1 " 4/20 " '2/ 2%%22%! 12 %0'27~8$ %!!

13 Literature E/ 5'0G,;HH#%% C I05? 0 "-2 # ;%' 20JJ

INHERITANCE - Part 1. CSC 330 OO Software Design 1

INHERITANCE - Part 1. CSC 330 OO Software Design 1 INHERITANCE - Part 1 Introduction Basic Concepts and Syntax Protected Members Constructors and Destructors Under Inheritance Multiple Inheritance Common Programming Errors CSC 330 OO Software Design 1