Лабораторно упражнение No 4 Работа с класове и обекти в С++

cout<

}
int compare( const void *arg1, const void *arg2 )

{

return (*( int * ) arg2 - * ( int * ) arg1) ;

{

MyArray m;

m.sort();

m.output();

}
Пуснете програмата в средата на VC++ и я тествайте как работи. Изяснете си използването на qsort.

1. 
   Разгледайте Exam3.cpp. Пуснете програмата в средата на VC++. Обяснете си обектният модел на прозореца, който е реализиран в примера. Какво е предназначението на връщана стойност псевдоним към класа, използван в повечето методи? Как се реализира?
   
2. 
   Създаите клас за работа с низове и предефинирайте операциите <<, >>, ==, !, +, += и = за него. Сравнете решението си с Exam4.cpp. Използвахте ли копи-конструктор и защо?
   
3. 
   Разгледайте Exam5.cpp. Обяснете си наследяването и виртуалните методи. Какво ще се разпечати на екрана? Пуснете програмата и проверете правилността на отговорите си.
   
4. 
   Решете всички разглеждани досега примери чрез класове.
   

#include

#include

#include

#include

const char BELL='\007';

class Screen {

short height,width;

char *cursor,*screen;

Screen & home() { move(0,0); return *this; }

void checkRange(int,int);

row();

public:

Screen & reSize(int,int,char='#');

Screen & lineX(int,int,int,char);

Screen & display();

Screen & down();

Screen & forward();

Screen & set(char *);

Screen & set(char);

isEqual(Screen &);

void copy(Screen &);

Screen (int=8,int=40,char='#');

~Screen();

};

void lineY(Screen & s,int row,int col,int len,char ch)

for(int i=0;i

}

void Screen::checkRange(int row,int col)

{ cerr<<"Coordinate ("<

exit(1);

}

}

{ int pos = cursor-screen+1;

return ((pos+width-1)%width)+1;

}

inline Screen::remSpace()

return (screen+sz-cursor-1);

}

Screen & Screen::move(int r,int c)

int row = (r-1)*width;

cursor = screen+row+c-1;

return *this;

}

Screen & Screen::reSize(int h,int w,char bk)

char *pNew = ps->screen;

char *pOld = screen;

while (*pOld && *pNew) *pNew++ = *pOld++;

this->Screen::~Screen();

*this = *ps;

return *this;

}

Screen & Screen::lineX(int row,int col,int len,char ch)

for(int i=0;i

return *this;

}

Screen & Screen::display()

for(int i=0;i

{ cout<<'\n';

int offset = width*i;

for(int j=0;j

{ p=screen+offset+j;

cout.put(*p);

}

}

}

Screen & Screen::down()

else cursor += width;

return *this;

}

Screen & Screen::forward()

if(*cursor=='\0') home();

return *this;

}

Screen & Screen::set(char *s)

int len=strlen(s);

if (space

{ cerr<<"String will be truncated from position "<

". New string length will be "<

len=space;

}

for (int i=0;i

return *this;

}

Screen & Screen::set(char ch)

cerr<<"Symbol NULL is ignored.\n";

else *cursor=ch;

return *this;

}

Screen::isEqual(Screen & s)

char *p=screen,*q=s.screen;

if(p==q) return 1;

while(*p && *q && *p++==*q++) ;

if(*p || *q) return 0;

return 1;

}

void Screen::copy(Screen & s)

height=s.height;

width=s.width;

screen=cursor=new char[height*width+1];

if(screen==NULL)

{ cerr<<"Out of memory.\n";

this->Screen::~Screen();

exit(1);

strcpy(screen,s.screen);

}

Screen::Screen(int high,int widt,char bkgr)

height=high;

width=widt;

cursor=screen=new char[sz+1];

if(screen==NULL)

{ cerr<<"Out of memory.\n";

this->Screen::~Screen();

exit(1);

char *ptr=screen,*endptr=screen+sz;

while(ptr!=endptr) *ptr++=bkgr;

*ptr='\0';

}

Screen::~Screen()

}
void main(void)

{ Screen X(3,3),Y(3,3);

// clrscr();

cout<<"Objects are equal "<

Y.reSize(6,6);

cout<<"Objects are not equal "<

lineY(Y,1,1,6,'*'); lineY(Y,1,6,6,'*');

Y.lineX(1,2,4,'*').lineX(6,2,4,'*').move(3,3);

Y.set("hi").lineX(4,3,2,'^').display();

X.reSize(6,6);

cout<<"\n\nObjects are not equal "<

X.copy(Y);

cout<<"Objects are equal "<

cin.get();

}
Exam4.cpp

#include

#include

class String {

friend ostream& operator << (ostream&,String);

friend istream& operator >> (istream&,String&);

friend String operator + (String,String);

public:

String(int);

String(char *);

String(String&);

~String(void);

int operator ! (void);

int operator == (String);

String& operator += (String);

String& operator = (String);

String& operator = (char *);

private:

char *str;

int len;

};
String::String(int ln)

{

len=ln;

str[0]='\0';

}
String::String(char *s)

{

len=strlen(s);

strcpy(str,s);

}
String::String(String &st)

{

len=st.len;

strcpy(str,st.str);

}
String::~String(void)

{ if (len)

delete str; }
int String::operator ! (void)

{ return (len==0); }

{ return (strcmp(str,st.str)==0); }

{

char *s = new char[len+1];

len+=st.len;

String::~String();

str=new char[len+1];

strcpy(str,s);

strcat(str,st.str);

return *this;

}
String& String::operator = (String st)

{

String::~String();

str=new char[len+1];

strcpy(str,st.str);

return *this;

}
String& String::operator = (char *s)

{

String::~String();

str=new char[len+1];

strcpy(str,s);

return *this;

}

String operator + (String st1,String st2)

String s=st1;

s += st2;

return s;

}
ostream& operator << (ostream &os,String st)

{ return (os<
istream& operator >> (istream &is,String &st)

{

char inBuf[SIZE];

st=inBuf;

return is;

}
void main(void)

{

String s1,s2,s3;

cout<

s3 = s1+s2;

cout<

s3 = s1;

s3 += s2;

cout<

}
Exam5.cpp

#include

#include

enum ZooLocs{ZOOANIMAL,BEAR,PANDA};

static char *locTable[]={

"Whole zoo area",

"North B1: brown area",

"East B1,P area" };

class ZooAnimal {

friend void print(ZooAnimal *);

public:

virtual ~ZooAnimal() { delete name; }

void link(ZooAnimal *);

virtual void print();

virtual void isA();

protected:

char *name;

ZooAnimal *next;

};

class Bear:public ZooAnimal {

Bear(char *s="Bear",ZooLocs loc=BEAR,char *sci="Ursidae");

~Bear() { delete sciName; }

void print();

void isA();

protected:

char *sciName;

ZooLocs ZooArea;

};

class Panda:public Bear {

Panda(char *,int,char *s="Panda",char *sci="Ailuropoda Melaoleuca",

ZooLocs loc=PANDA);

~Panda() { delete indName; }

void print();

void isA();

protected:

char *indName;

int cell;

};

ZooAnimal::ZooAnimal(char *s):next(0) {

strcpy(name,s);

}

void ZooAnimal::link(ZooAnimal *za)

next=za;

void ZooAnimal::isA()

{ cout<<"Animal name: "<

}

void ZooAnimal::print()

}

Bear::Bear(char *s,ZooLocs loc,char *sci):ZooAnimal(s),ZooArea(loc)

strcpy(sciName,sci);

}

void Bear::isA()

cout<<"\tSname: \t"<

}

void Bear::print()

cout<<"\tAdress: \t"<

}

Panda::Panda(char *nm,int room,char *s,char *sci,ZooLocs loc):

indName=new char[strlen(nm)+1];

strcpy(indName,nm);

};

void Panda::isA()

cout<<"\tCall our friend: \t"<

}

void Panda::print()

cout<<"\tCell No: \t"<

}

void print(ZooAnimal *pz)

{ pz->print();

cout<<'\n';

pz=pz->next;

}

}
ZooAnimal *headPtr=0,circus("Circus animal");

Panda yinYang("Yin Yang",1001,"Big Panda"),

rocky("Rocky",943,"Red Panda","Ailurus fulgena");
ZooAnimal * makelist(ZooAnimal *ptr)

{ ptr=&yinYang;

ptr->link(&circus);

ptr->link(&yogi);

ptr->link(&rocky);

return ptr;

}
void main()

{ cout<<"Virtual Function Example\n";

headPtr=makelist(headPtr);

print(headPtr);