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Issue with inheritance

jj09786 (22)
I made this little code to try understanding more the concept of inheritance
and I came to a problem.

At the line where I told Luis to attack Gerry (In Main.cpp), the compiler dropped an error that says : no matching function to call to 'Wizard::attack(Character&)'

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//MAIN.CPP

#include <iostream>
#include "Character.h"
#include "Wizard.h"

using namespace std;

int main()
{
    Wizard Luis;
    Character Gerry ;
     cout<<"Gerry Attack Luis"<<endl;
    Gerry.attack(Luis);
     cout<<"Gerry ";
    Gerry.showlife();
     cout<<"Luis ";
    Luis.showlife();
     cout<<"Gerry "<<endl;
    Luis.attack(Gerry);                    //this line here
     cout<<"Gerry ";
    Gerry.showlife();
     cout<<"Gerry ";
    Luis.showlife();
     cout<<"Gerry drink a potion, now he got : ";
    Gerry.heal(20);
    return 0;
}

//WIZARD.CPP

#include "Wizard.h"

using namespace std;

Wizard::Wizard() :Character(),m_mana (75),m_Fire_dmg(17)
{

}


void Wizard::fireball (int m_Fire_dmg, int m_dmg)
{
  m_vie -= (m_Fire_dmg += m_dmg);
  cout<<" is throwing a Fire Ball at ";
}

void Wizard::attack (Wizard &target)

{
    target.fireball(m_Fire_dmg,m_dmg);
}


//CHARACTER.CPP

#include "Character.h"
#include "Wizard.h"
#include <iostream>

using namespace std;

Character::Character():m_vie(100),m_dmg(23),m_potion(20)
{

}


void Character::getdmg (int m_dmg)
{
 m_vie -= m_dmg;
}

void Character::attack (Character &target)
{
 target.getdmg(m_dmg);
}


void Character:: heal (int m_potion)
{
 m_vie += m_potion;

  if (m_vie>100)
   {
    m_vie = 100 ;
   }
  cout<<m_vie<<" HP"<<endl;
}

 void Character::showlife ()const
{
 cout<<" a "<<m_vie<<" HP"<<endl;
}


Is it possible that the compiler's throwing that error because it need to sort of convert one of the object to make them able to interact together?
Like Character is not a Wizard type?
Last edited on
helios (17574)
You forgot to post Wizard.h and Character.h.
Mops (17)
You made a little mistake.

void Wizard::attack (Wizard &target)

This means your wizard object can only attack other wizard objects.
You have to do this.

void Wizard::attack (Character &target)

This way your wizard object can attack all character objects aswell as wizard objects.
You also have to change the attack function of wizard since you are calling a function that only wizard has.

target.fireball(m_Fire_dmg,m_dmg); //this
jj09786 (22)
Can you explain to me what is actually wrong with ;target.fireball(m_Fire_dmg,m_dmg); I'm not sure I quite understand what you are thinking actually, It seems to me that if I correct the declaration of the method like you told me :void fireball (Character & target), only wizard will be able to cast a fireball am I wrong?, I just need more precise explanation, english ain't my primary labguage so.. Thx for your comphrension


BTW : I'll import both Wizard.h and Character.h afterwork to this thread
Last edited on
AbstractionAnon (6954)
Can you explain to me what is actually wrong with ;target.fireball(m_Fire_dmg,m_dmg);

Your fireball function is a member of your Wizard class. Since you invoke it as target.fireball(), target must be a Wizard. Character has no such function, so your target can't be a Character.

If you want a Wizard to throw a fireball at another character (which might be another Wizard), I would make the signature look like this:
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void Wizard::throw_fireball (Character & target)
{  //  Now we can manipulate the attributes of the target Character
}
...
  Luis.throw_fireball (Gerry);
  //  Note that Gerry can't throw a fireball at Luis because Gerry is not a Wizard.


If you want any Character to be able to throw a fireball (which I doubt), then make throw_fireball() a member of the Character class.
Last edited on
jj09786 (22)
I have fixed my method with your advise and the compiler compiled it, I have remove the void Wizard::attack() method and merge it into the void Wizard::fireball() method

/
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//Wizard.cpp


#include "Wizard.h"

using namespace std;

Wizard::Wizard() :Character(),m_mana (75),m_Fire_dmg(17)
{

}


void Wizard::fireball (Character &target)
{
  m_vie -= (m_Fire_dmg += m_dmg);
  cout<<" is throwing Fireballs at ";
}


//Main.cpp

#include <iostream>
#include "Character.h"
#include "Wizard.h"

using namespace std;

int main()
{
    Wizard Luis;
    Character Gerry ;
     cout<<"Gerry Attack Luis"<<endl;
    Gerry.attack(Luis);
     cout<<"Gerry ";
    Gerry.showlife();
     cout<<"Luis ";
    Luis.showlife();
     cout<<"Luis ";
    Luis.fireball(Gerry);
     cout<<"Gerry "<<endl;
      cout<<"Gerry "<<endl;
    Gerry.showlife();
     cout<<"Luis "<<endl;
    Luis.showlife();
     cout<<"Gerry drink a potion, now he got : ";
    Gerry.heal(20);
    return 0;
}

When you execute it, the problem seems to be Luis throwing a Fireball at 127.0.0.1 ahaha
seriously it won't throw a fireball at Character
AbstractionAnon (6954)
Look at lines 15-19. What variables are you accessing? Hint: You're accessing the Wizard's damage values. Don't you want to be updating the target's damage variables?

Still haven't seen the header for character.h or wizard.h you said you would post.



jj09786 (22)
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//Character.h


#ifndef CHARACTER_H
#define CHARACTER_H
#include <iostream>


class Character

{
  public:

   Character ();

    void getdmg (int m_dmg);
    void attack (Character &target);
    void heal (int m_potion);
    void showlife ()const;
    void s_attack(Character &target);




  protected:

    int m_vie = 100;
    int m_potion = 20;
    int m_dmg = 23;

};

#endif // CHARACTER_H


//Wizard.h


#ifndef WIZARD_H
#define WIZARD_H
#include "Character.h"


class Wizard : public Character
{
    public:
        Wizard();
        void fireball (Character &target);



    protected:

    private:

    int m_mana = 75;
    int m_Fire_dmg= 17;


};

#endif // WIZARD_H


So i must put like
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void Wizard::fireball (Character &target)
{
 
target.    m_vie -= (m_Fire_dmg += m_dmg)  // Wrap all those attributs  into a function that update target's damage variable
 
  cout<<" is throwing Fireballs at ";
}


Am I Wrong?
Last edited on
AbstractionAnon (6954)
Am I Wrong?

That depends on what you're trying to do.

Line 5: You're adding the Wizard's dmg variable to the the Wizard's fire_dmg variable. Not sure why you're doing this. Did you intend to make the Wizard's fireball strength greater for each fireball thrown? One might assume that the Wizard has only a certain amount of fireball strength and is weakened, not strengthened for each fireball thrown.
 
 
target.m_vie -= (m_Fire_dmg += m_dmg)

Then you're taking the (updated) Wizard's fire_dmg and subtracting that that from the targets m_vie. This part makes sense.

jj09786 (22)
The m_dmg (normal attack damage) variable stand for the damage that Character can afflict tought, The m_Fire_dmg (fire attack damage) stand for the damage That Wizard afflict. My point is , We know that Wizard is a Character so I just want Wizard to sum the m_dmg and the m_Fire_dmg so it will represent the total damage that fireball is making. m_dmg+=m_Fire_dmg and after that I want to substract the sum of the 2 variable that represent the general damage of their object to m_vie who represent the health of Character and the Health of Wizard too, but in my case I still want to Attack Gerry the Character with the Luis's fireball
Last edited on
jj09786 (22)
I Finally made it , thanks for your patience, I guess I'll need to read more about the whole concept of Class , Inheritance and pointer, there's always some details missing for some of my question with the information I end up with...

This is what I made

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void Wizard::fireball (Character &target)
{
  m_Total_dmg = m_dmg+m_Fire_dmg;
  target.getdmg(m_Total_dmg);
  cout<<" is throwing a Fireball at  ";
}


getdmg() who belong to Character is finishing the request of Wizard for attacking a Character

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void Character::getdmg (int m_dmg)
{
 m_vie -= m_dmg;
}


If you have a better Idea of how I should make this work I'm totally open for new idea or challenges for educational prupose, thx again!!
AbstractionAnon (6954)
If you have a better Idea of how I should make this work

You've got the right idea.

A few of comments though:
1) line 5: Why is m_total_dmg a member variable? It can just be a local variable. Do you really need to save this value? I don't see that it adds any value to a Wizard.

2) target.getdmg(). This is a good idea to add to Character to allow adjusting its health. i.e. taking a hit. However, I would suggest naming this take_damage or something similar. get_xxx usually implies a getter which returns a value, rather than a modifier that adjusts a value.

3) I had earlier suggested renaming fireball to throw_fireball, making clear the action that is being taken and by whom.

4) getdmg() I would not suggest naming the argument with a m_ prefix. The m_ prefix is usually used to indicate a member variable. An argument is not a member variable.

jj09786 (22)
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void Wizard::fireball_cast (Character &target)
{
  m_Total_dmg = m_dmg+m_Fire_dmg;
  target.attack(m_Total_dmg);
  cout<<" is throwing a Fireball at  ";
}

........

void Character::attack (int total_dmg)
{
 m_vie -= total_dmg;
}

void Character::norm_attack (Character &target)
{
 target.attack(m_dmg);
}



1) 2) 3) and 4) haha ;)

Thanks AbstractionAnon for the hand that you've been giving to me , Hope of seeing you in another thread

Peace
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