[Help]virtual methods, constructors, destructors.

I would appreciate explanations, my book does a bad jawb explaining

patrick? o_O

Originally Posted by why06

patrick? o_O

yes, nao explain

Originally Posted by rtemis

I would appreciate explanations, my book does a bad jawb explaining

Buy another book.

Originally Posted by Void

Buy another book.

Or you could take a couple minutes and explain

what book do you have?

It's a long explanation and I'm tired.

Super short version:
Virtual: virtual things can be used by classes that inherit that base, but not by the base class itself. The reason being is that method has to be defined somewhere. virtual things are not real untill a class implements that virtual method. The advantage fo doing this is a base class pointer can call methods in it's child classes whitout specifying or knowing exactly what each will do.

Costructors: Makes class object, allocates memory, assigns variables, etc.

Destructor: Deletes object.

virtual methods: methods that can be overridden by a derived class.

constructors: code called when object is created. usually used to create mem / resources and initialise variables and data.

destructors: code called when object is destroyed. usually used to free mem / resources. you spelt that wrong btw...

classes.cpp

Code:

Animal::GetAnimalType()
{
    return "I'm a generic animal!";
}

Dog::GetAnimalType()
{
    return "I'm a dog!";
}

Cat::GetAnimalType()
{
    return "I'm a cat!";
}

Korean::GetAnimalType()
{
    return "I AM A HOMOSEXUAL KOREAN!!!!!!!";
}

classes.h

Code:

class Animal
{
public:
    virtual char *GetAnimalName();
};

class Dog : public Animal
{
    char *GetAnimalName();
};

class Cat : public Animal
{
    char *GetAnimalName();
};

class Korean : public Animal
{
    char *GetAnimalName();
}

main.cpp

Code:

#include <iostream>
#include "classes.h"
using namespace std;

int main()
{
    Animal *Anus[4];
    Anus[0] = new Animal;
    Anus[1] = new Dog;
    Anus[2] = new Cat;
    Anus[3] = new Korean;
    for(int i = 0; i < 4; i++)
    {
         cout<<Anus[i]<<endl;
    }
    return 1;
}

Or something in that direction.
Basicly virtual functions can be overwritten by classes that inherit from it. I used it in my D3D menu.
GUIButton, GUITextbox and GUILabels etc all inherited GUIObject which had some generic virtuals:
void Render();
bool TestClick(int x, int y, bool bDouble);

and things like that. that way i could just iterate over the GUIObject vector to test clicks and have everything rendered in just 4 lines(since each object implemented its own rendering system)

nvm, turns out my book didnt get the point across quite well.

[Help]virtual methods, constructors, destructors.

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