intro_c_cpp lesson 9 fall_10

8/6/2019 Intro_C_CPP Lesson 9 Fall_10

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Introd to C/C++(Section 2) Week 9 1

Introduction to C/C++

Yedidiah Solowiejczyk

Week 9


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Sy nopsisReview of Classes in C++

Declaring classesInitializing class member variablesPublic vs. private member functionsConstructors & DestructorsInheritancePol ymorphism

Virtual Member Functions Overriding Member Functions

Standard Libraries math.h, stdlib.h, etc

More on Exotic Pointers. Link Lists Binar y Trees Binar y Search


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A Brief Histor y of C++

C++ Programming 1980 Stroustrop at Bell Labs extended the C

programming language to include the concept of class combining data with the respective functions that

manipulate the data Object-Oriented Programming (OOP)

Encapsulation Strong data typing

Inheritance Reusability

Polymorphism Run-time functionality


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Object Oriented Programming

Encapsulation The abilit y to define new data t ypes and set of

operations ( functions) governing the new t ype

Inheritance class derivation The abilit y to create new t ypes that inherit properties

from exiting t ypes

Pol ymorphism The abilit y of objects that belong to related classes to

respond differentl y to the same operationVirtual functions


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C programming vs. Object Oriented Programming

C programming Structured Language

Decomposition of task into procedures(functions)

Data is handled separatefrom procedures Prone to errors becauseof separation betweendata and functions

C++ OOP Language

Builds strong link between the datastructures and the

methods that manipulatethe data Think of objects & their

behavior Mammals Persons

Mobile phones Satellite vehicles Geometric Shapes


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Classes in C++Structure

collection of variables of differenttypes

contained within a name (tag)

Class collection of ( member ) variables of

different t ypes combined with a set of related

(member) functions

contained within a name (tag)

Classes encapsulate the data and functions

into one collection the object .

Encapsulation makes programming and

maintenance easier Ever ything is one place C++ imposes a built in discipline

Example

class cat // template of an object{private: // protected area

unsigned int A ge; // data membersunsigned int Weight;

public:// member function

void Meow( );

};// member function declarationvoid Meow( void);int main( ){

cat X; //instantiate ( object ) XX.Meow; //invoke methodX.A ge = 5; //forbidden private

}void Cat::Meow( ) // class definition{ cout


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Class SkeletonPrivate member data members protect data in class from being

erroneousl y modified from theoutside the class Privatize data members

Public member functions Socialize (make public)

member functions allow access to private parts via

built-in functions ( publicaccessor ) Ever y public member function

has access to the private datamembers

Member function definition use scoping operator :: int cat::get A ge( )

{::::::::

}

Exampleclass cat // class declaration or protot ype{

// private: - b y defaultint A ge;int Weight;

public: // public member functionsvoid set A ge(int x){ A ge = x;} //inlinevoid setWeight(int y){Weight = y;}int get A ge(){return A ge;}int getWeight();void Meow();

};int main (){

cat X;int temp;X.set A ge(6);X.setWeight(20);temp = X.get A ge( );temp = X.getWeight( );

}// access thru scoping operator ::int cat::getWeight() {return Weight;}void cat::setWeight(int W){weight = W;}


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ConstructorsConstructors

Constructor - is unique member functionthat is used for initializing the datamembers of a class

Constructors can take parameter s but itis not mandatory

Constructors cannot return a value even void

Constructor has the same name as class Default constructors if you do notdeclare a constructor the compiler willprovide one automaticallyConstructors declarations cat::cat(int age, int weight); cat::cat(int age); cat::cat( ) default constructor

If you provide a constructor then default constructor will not be provided automatically by compiler you should create your own

Exampleclass Cat // protot ype (declaration){private:

int A ge, Weight, Id;public:// constructors

Cat(int age, int weight, int id);Cat( );// default constructor

// member functionsint get A ge(){return A ge};

int getWeight() (){return Weight}; //inline fnctvoid Meow();

};int main(){

Cat X(5,20,35); //constructorsCat Y;

}Cat::Cat(int age, int weight, int id) //definitions

{ A ge = age;Weight = weight;Id = id;

}Cat::Cat( ) // default constructor{A ge = 0; Weight = 0; Id = 0;}


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Destructors Destructor - is a unique member function cleans up after object goes

out scope de-allocates memory Destructors have always the name of the class

Destructors are always preceded with~

Destructor never take argumentsDestructors never return a value

Destructor declarationcat::~cat(){ } // takes no actionThere is onl y one destructorIf you do not provide adestructor, the compiler will

provide one

class Cat // protot ype (declaration){private:

int A ge, Weight, Id;public:

Cat(int age, int weight, int id); // constructorsCat( );// default constructor~Cat( ); //destructorint get A ge(); //other member functionsint getWeight();

void Meow();};int main(){

Cat X(5,20,35);Cat Y;

}Cat::Cat(int age, int weight, int id) //definitions

{A ge = age;Weight = weight;Id = id;

} // default constructorCat::Cat( ) {A ge = 0; Weight = 0; Id = 0;}Cat::~Cat( ){ cout


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Friend FunctionsF riend member function doesexactl y what other memberfunctions except that it hasaccess to private members of oneor more classes

class tax; // announcement

class customer { int cost_item;

public:customer(){balance = 0;}

friend void PRINT(customer x, tax y);

}

class tax { int rate;

public:tax( ){rate = 0;}

friend void PRINT(customer x, tax y);

};void PRINT(customer x, tax y){

cout


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Inheritance A class that adds new functionality to

an existing class is said to be derived from the original ( base ) class

A class inherits from its base classmany of its attributes

Single inheritance derived from asingle class

class A ;class B: public A

Multiple inheritance derived fromtwo or more classes

class A ;

class B;class C: public A , public B; //Inheritance is-a relationship

Single Inheritance

Shape Attributes

int X;Int Y;

Square Rectangle

CirclePoint Center(5);


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InheritanceClass inheritance allowsmembers of one class to be usedas if the y were members of asecond class

A derived class can inherit from

its base class in three wa ys: public private protectedExamples class Student:public Person;

class Y:private X; class A :protected B ;

A class can contain three t ypes of members: public

Visible outside the class

private Accessible only thru public

member functions

protectedA ccessible onl y thru publicmember functionsProtected data & functions are

fully visible to derived classes


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InheritanceInheritance

Publicmemb

Privatememb

Protectedmemb

public Public Private Protected

private Private Private Private

protected Protected Private Protected

m e mb ers

INHER

ITs

ACCE

Ss

A pu b lic m e mb er is accessi b leto a pu b licly derived class

A private m e mb er is notaccessi b le to derived classes

A protected m e mb er function arefully visi b le to derived classes b ut

otherwise private

Inheritance Li m itationsThe following

operations are notinherited

ConstructorsDestructorsOverloaded operators


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Inheritance If a base class and a derived class

have identical named publicfunctions with the same signature , invoking the function in the derivedclass overrides the base function

Exampleclass Shape {public :void setColor(int new_color);void move(int x, int y);void Print( ){cout


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Virtual Functions#define PI 3.14159class Shape {public:void setColor(int new_color);void move(int x, int y);virtual float area( ){return -1;}virtual float perim( ){return -1;}//constructors//destructorsprivate:int x, y; //center of shape};class Circle:public Shape { //derivedprivate:int r;public:virtual float area( ){ return (PI*r*r);}};

class Rectangle:public Shape{//derivedprivate:int u, v;public:virtual float area( ){ return (u*v);}virtual float perim( ){retrun (2*u + 2*v;}};int main(){

Shape *p; // pointer to shapeCircle c;Rectangle r;int flag = 1;

if( flag ==1 )p = &c; //point to circle

elsep = &r; //point to rectangle

p->area( ); //get area ????

}


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Standard Libraries

C STANDARD LIBRARYContains function prototypes, type and m acro definitions

#include - character handling #include - error handling

#include - string handlingint strlen(char *s1), int strc m p(char *s1, *char *s2), etc #include - big and small numbers

INT_MAX 32767, INT_MIN -32767

#include - catch all

Random # generator #include - date and time #include - sin, cos, tan, etc


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Random Number Generators#include

#include //contains the function prototype for rand( )

int main( ){

int i , seed; printf("Enter random number seed prime

#\n");scanf("%d" , &seed);

srand(seed); // init random numbergeneratoor

for(i = 0; i < 5; i++) printf("%12d" , rand( ));

printf("\n ------- Normalized Random Numbers ----\n");for(i = 0; i < 5; i++)

printf("%12d" , rand( )/32767 );

printf("\n");

}

[solowiejczyk@sweng191 Jed]$ !mamake Randomcc Random.c -o Random[solowiejczyk@sweng191 Jed]$ ./RandomEnter random number seed prime #11804289383 846930886 1681692777 1714636915 1957747793

------- Normalized Random Numbers ----12947 21969 50348 18204 36306

[solowiejczyk@sweng191 Jed]$ ./RandomEnter random number seed prime #31205554746 483147985 844158168 953350440 612121425


[solowiejczyk@sweng191 Jed]$ ./RandomEnter random number seed prime #171227918265 3978157 263514239 1969574147 1833982879


[solowiejczyk@sweng191 Jed]$


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TemplatesTemplates are patterns from whichclasses can be created

ExampleTemplate class A rra y{public:

A rra y(int Size); // constructor~ A rra y( ){delete [ ] A rra y _ptr ;}

int get Size(){return size;}private:

int size;Type *A rra y _ptr;

};A rra y:: A rra y(int Size){

size = Size;A rra y _ptr = new Type [size]; //Heap

}

int main(){

Array A[4]; //array 4 intsArray F[12];

{Array C[32];

}//destro y C after going out of scope}


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Linked Listlinked list - is a data structure that consists of a sequenceof data records such that in each record there is a field thatcontains a reference (i.e. , a l ink ) to the next record in thesequence.

The principal benefit of a linked list over a conventional array is thatthe order of the linked items may be different from the order that thedata items are stored in memory or on disk. For that reason , linked listsallow insertion and removal of nodes at any point in the list , with aconstant number of operations.

On the other hand , linked lists by themselves do not allow randomaccess to the data , or any form of efficient indexing. Thus , many basicoperations such as obtaining the last node of the list , or finding anode that contains a given datum , or locating the place where a newnode should be inserted may require scanning most of the listelements.



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Linked Listsstruct node {int value;struct node *next;};

struct node X1, X2,X3, X4;strcut node *temp;X1.value = 5;X1.next = &X2;X2.value = 6;X2.next = &X3X3.value= 7;X3.next = NULL

X1 X2 X3

value valuevalue NULL

X4

value

Link Lists are used when you need to maintain a disorganized listof items that can be dynamically allocated and de-allocatedExample: Modeling communications center receiving & dropping random calls

temp.next = X1.nextX1.next = &X4;X4.next = temp.nextX4.value = 12;


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Binar y Tree Structures

Binar y tree is a data structure in

which each node has at mosttwo children

struct node {char fruit[32];char descri b er[128];struct node *left;struct node *right;};

Searches are quick~ log 2(N) fast rather than N

lemon

date pear

grape orange quince berry


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Binar y Search Problem: Given an sorted list of values (names) ,

what is average # searches that are necessary tofind a random value (name)?Linear Search - probing each name in the list , willtake on the average N/2 comparisons

Binary Search algorithm is implemented by jumping to middle of array and testing target namevs. array name (equal , smaller , larger)

Algorithm requires log 2 (N) vs. O(N) e.g. log 2 (1024) ~ 10 attempts vs. O( 1024/2 )


Benson |Doe | Frank ||Julian| **|Oscar |** | Zorba

intro_c_cpp lesson 9 fall_10

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