Polymorphism with virtual function

[patriic48]

error C4700: uninitialized local variable 'a' used in main.cpp

I want to use virtal void sounds() - function but can´t get it to work.

Don´t know what I´m doing wrong here. Anybody knows how to do the magic?

  //Animals.h - Base/Parent Class
//Animal class definition.

#ifndef ANIMALS_H
#define ANIMALS_H

#include <iostream>
#include <string>

using namespace std;

class Animals {
public:
	//Default Constructor
	Animals(); // : name(""), speed(0), eating("") {}

	//Overload Constructor
	//Animals(string theName, int theSpeed, string theEating);
	Animals(string, int, string);

	//Accessor Function
	string getName() const;
		//getName - returns name
		//@return string - name

	int getSpeed() const;
		//getSpeed - returns speed
		//@return string - speed

	string getEating() const;
	//getEating - returns eating
	//@return string - eating

	//Mutator Function
	void setName(string);
		//setName - sets Name

	void setSpeed(int);
		//setSpeed - sets Speed

	void setEating(string);
	//setEating - sets Eating

	//void setSound(string);
		//setSound - sets Sound

	//Destructor
	~Animals();

	void printInfo() const;
	//printInfo - print out name and speed

	//Virtual Function
	virtual void sounds()
    {
		cout << "Animals sounds different.\n"; 
	}

private:
	string name;
	int speed;
	string eating;
	
}; 

#endif 

//Herbivores.h

#ifndef HERBIVORES_H
#define HERBIVORES_H

#include <iostream>
#include "Animals.h"

using namespace std;

class Herbivores : public Animals 
{
public:

	//Default constructor
	Herbivores();

	//Overload Constructor
	Herbivores(string, int, string); //One more string?

	//Accessor Function:

	string getHerbs() const;
		//getHerbs - returns herbs
		//@return string - herbs

	//Mutator Function

	void setHerbs(string);
		//setName - sets Name

	//Destructor
	~Herbivores();

	void printInfo() const;
	// printInfo - prints the properties
	
	virtual void sounds()
    {
		cout << "Herbivores sounds \x22iaiaiaia\x22.\n"; 
	}

private:
  string herbs;
};

#endif 

//main.cpp

#include "Animals.h"
#include "Herbivores.h"
#include "Carnivores.h"

using namespace std;

int main() {

	Animals *a;
	Herbivores h;

	//a.sounds();
	a->sounds();

	h.setName("Rabbit");
	h.setSpeed(100);
	h.setHerbs("Carrot");
	h.printInfo();
	h.sounds();
	
	a = &h; /*Address of object h in pointer variable */
	a->sounds();
	
	cout << endl;

	return 0;
}

[ajh32]

Well, in your main() function you have declared a variable for a pointer to an Animals instance 'a' but it is currently pointing at rubbish as it hasn't been initialised:

Animals* a = new Animals();

...

delete a;
a = NULL;

[patriic48]

ahh okey, now I understand! Thank you ajh32!

/ P