default constructor for child classes?

[Claymz]

Hi,

is it possible to make default constructor for derived classes? Or can default constructor only be the parent class itself?

TY

[Disch]

Any class can have any constructor.

[Claymz]

//parent class
{
mName = "DefaultName";
mPosition = Vector3(0.0f, 0.0f, 0.0f);
mVelocity = Vector3(0.0f, 0.0f, 0.0f);
mFuelLevel = 100;
mDamage = 0;
}
Spaceship::Spaceship(const string& name,
const Vector3& pos,
const Vector3& vel,
int fuel,
int damage)
{
mName = name;
mPosition = pos;
mVelocity = vel;
mFuelLevel = fuel;
mDamage = damage;
}


//child class
class FighterShip : public Spaceship
{
public:
FighterShip(
const string& name,
const Vector3& pos,
const Vector3& vel,
int fuel,
int damage,
int numMissiles);
private:
int mNumMissiles;
};
FighterShip::FighterShip(const string& name,
const Vector3& pos,
const Vector3& vel,
int fuel,
int damage,
int numMissiles)
: Spaceship(name, pos, vel, fuel, damage)
{
mNumMissiles = numMissiles;
}

is it possible to to make FighterShip fighter()? (because we didnt even define a default constructor for FighterShip, which has one more method added to its parameter)

[Disch]

is it possible to to make FighterShip fighter()?

Only if FighterShip has a default constructor.. Which yours doesn't. So with that code, no, you can't default construct a FighterShip.

You could make a default constructor for it, though:

class FighterShip : public Spaceship
{
public:
    // make this constructor the default constructor
    FighterShip(
        const string& name = "Nameless FighterShip",
        const Vector3& pos = Vector3(0,0,0),
        const Vector3& vel = Vector3(0,0,0),
        int fuel = 100,
        int damage = 100,
        int numMissiles = 0);

private:
    int mNumMissiles;
};

Now that constructor will act as the default constructor, which means you can create Fighterships like so:

FighterShip defaultfighter;

PS: Learn to indent. Indentation and whitespace are your friend. Makes code much easier to read and follow.

[Claymz]

sry i meant FighterShip fighter...(without (), my bad)

i how would i make a default AND an user defined constructor? (as same as it is in parent class - you have 2 options: default or optional constructor)

i want to be able to do all of these things:

Spaceship defaultspaceship;
Spaceship optionalspaceship(......);
FighterShip defaultfighter;
FighterShip optionalfighter(........);

[Athar]

i how would i make a default AND an user defined constructor? (as same as it is in parent class - you have 2 options: default or optional constructor)

No, you have way more than those two options.
You can have any number of constructors in a class, since you can overload constructors like any other function.

[Kyon]

There are 3 main TYPES of constructors. Default, Copy and "normal".
A default constructor is merely a constructor with:
A) No input parameters
B) Default values for the parameters
A copy constructor is a constructor in which you input an object of the same class you wish to instantiate an object off, copying the values the inputted object had.
A normal constructor is just all that remains, a constructor that can have default values, for which you must supply input apart from another object of the same class.
There is no such thing as a user-defined constructor, since ALL are user-defined when written in your code.

[Claymz]

Ok, i figured out everything now, thanks to you!