failed with inheritance~

[black]

Hi, all~

after reading the chapter of inheritance, I couldnt help testing it. but I failed with my first test, is there anything omitted ???

my code in short is:

class Vehicle
{
  //my code about class Vehicle;
};
class Car : public Vehicle; 

[SilentStrike]

class Car : public Vehicle {
// with all pure virtuals implemented
};

[black]

Originally posted by SilentStrike
class Car? public Vehicle {
// with all pure virtuals implemented
};

shall I fill it with a new constructor ? I tried but failed a second time. the code is right below:

class Vehicle
{
  //my code about class Vehicle;
};
class Car : public Vehicle
{
  public:
    Car(string, int, int)
    {
      cout << "I'm a car !";
    }
  private:
    int door;
}; 

[black]

no response ? my goodness !

[raimo]

Code works for me, after replacing Car(string, int, int) with Car(std::string s, int j, int k) and adding the appropriate headers. What is the problem?

[Boksha]

Yep, the classes look fine to me too.
Also, there might indeed be a problem with the constructor, maybe compiler specific. Try if it works when you make a constructor without any input.

[SilentStrike]

Does the Vehicle class have a default (takes no arguments) constructor? If so, it looks like that code should work.

[black]

it works at last but something confused me. Let's glimpse code first:

#include <iostream>
#include <string>

class Vehicle
{
  public:
    Vehicle(string, int, int);
    Vehicle();     
  private:
    string name;
    int tire;
    int speed;
};
Vehicle :: Vehicle(string s, int t, int sp)
{
  //...
}
Vehicle :: Vehicle()
{
  //...
}

class Car : public Vehicle{};

void main()
{
  Car myCar;
} 

it works fine, but the compiler would commit some mistakes when I build up a child class with the latter constructor which has 3 arguments just like this below:

void main()
{
  Car myCar("bicycle", 2, 15);
} 

Havent we inherited all the public member functions from the base class ?

[salvelinus]

Are you forgetting the using statement in Vehicle? Assuming you're using cout or something since you #include <iostream>

[salvelinus]

This code works:

#include <iostream>
#include <string>

using namespace std;

class Vehicle
{
  public:
    Vehicle(string, int, int);
    Vehicle();     
  private:
    string name;
    int tire;
    int speed;
};
Vehicle::Vehicle(string s, int t, int sp)
{
    name = s;
    tire = t;
    speed = sp;
    cout << name << ' ' << tire << ' ' << speed << endl;
}
Vehicle::Vehicle()
{
    cout << "Default constructor\n";
}

class Car : public Vehicle
{};

int main()
{
  Car myCar;
  Vehicle yourCar("pickup", 17, 55);
  return 0;
} 

but changing Vehicle yourCar... to Car yourCar... doesn't. That's because w/o a base class initializer, the default base class constructor is called, which doesn't take 3 arguments.
This works for Car

class Car : public Vehicle
{
    public:    
        Car::Car(){};
        Car::Car(string n, int t, int s) : Vehicle(n, t, s){};
}; 

That runs and compiles correctly. You have to add the default constructor to Car when you add the other one, at least in MSVC. W/o the 2nd constructor, you'll be able to use the default constructor in Vehicle.

[black]

Car::Car(string n, int t, int s) : Vehicle(n, t, s){};

what about this line please ??? I have never seen it before.

[salvelinus]

That's an initialization statement. In this case, it initializes the non default base class constructor. The Car constructor is passing the values in the Car declaration (in main) to the Vehicle constructor.
Check out help files on member and base class initialization.