Code Example for Memory Leakage #8

#include <iostream.h> 



class Fruit {

 double weight;

 char* color;

protected:

 Fruit(double, char*);

 Fruit(const Fruit&); public:

//Note the nonpolymorphic destructor

  ~Fruit();

// The correct destructor would look like:

// virtual ~Fruit();

 virtual void print();

};



Fruit::Fruit(double w, char* col)

{

 weight = w;

 color = new char[strlen(col)+1];

 strcpy(color, col);

}



Fruit::Fruit(const Fruit& rhs)

{



 weight = rhs.weight;

 color = new char[strlen(rhs.color)+1];

 strcpy(color, rhs.color);

}



Fruit::~Fruit()

{

 delete color;

}



void

Fruit::print()

{

 cout << ''\tFruit weight:'' << weight << ''\n'';

cout << ''\tFruitcolor:'' << color << ''\n'';

}



class Apple : public Fruit {

 char* variety;

public:

 Apple(double, char*, char*);

 Apple(const Apple&);

 ~Apple();

 void print ();

};



Apple:: Apple(double w, char* col, char* var) : Fruit(w, col)

{

 variety = new char[strlen(var)+1];

 strcpy(variety, var);

}



Apple::Apple(const Apple& rhs):Fruit(rhs)

{

 variety = new char[strlen(rhs.variety)+1];

 strcpy(variety, rhs.variety);

}



Apple::~Apple ()

{

 delete variety;

}



void

Apple::print()

{

 cout << ''Hi, I'm a'' << variety << ''Apple\n'';

 Fruit::print();

}

class Banana : public Fruit {

 char* export;

public:

 Banana(double, char*);

 Banana(const Banana&);

 ~Banana();

Banana::Banana(double w, char* exp) : Fruit(w, ''Yellow'')

{

 export = new char[strlen(exp)+1];

 strcpy(export, exp);

}



Banana:: Banana(const Banana&rhs):Fruit(rhs)

{

 export = new char[strlen(rhs.export)+1];

 strcpy(export, rhs.export);

}



Banana::~Banana()

{

 delete export;

}

void

Banana::print()

{

 cout << ''Hi, I'm a banana from '';

 cout << export << ''\n'';

}



main()

{

 Fruit *basket[20];

 int i, num;

 double weight;

 char color[128], variety[128], answer[128];

// The following code allows the user to

// interactively build a fruit basket of size

// 1 through 20.

 cout << ''How many fruit in the basket? '';

 cin >> num;

 if (num < 0 || num > 20) num = 10;

 for (i=0; i<num; i++) {

  cout << ''A)pple or B)anana? '';

  cin >> answer;

  if (answer [0] == 'a' || answer[0] == 'A' ) {

   cout << ''Apple's weight: ''; cin >> weight;

   cout << ''Apple's color: ''; cin >> color;

   cout << ''Apple's variety: ''; cin >> variety;

   basket[i] = new Apple(weight, color, variety);

  }



  else {

   cout << ''Banana's weight: '';

   cin >> weight;

   cout << ''Banana's country: '';

   cin >> variety;

   basket[i] = new Banana (weight, variety);

  }

}

for (i=0; i<num; i++) {

 basket[i]->print();

}



// If Fruit's destructor is not virtual,

// then this code will call Fruit's

// destructor num times. This will leak

// the memory used for the variety string in

// each Apple and the export string in each

// Banana.



 for (i=0; i<num; i++) {

  delete basket[i];

 }

}