Thread: class instantiation

I'm having a bit of a problem instantiating class objects in my program main function with respect to the syntax. Here are some code that illustrates my class declaration, method declaration, and driver:

Car.h:

Code:

#include "rt.h"                              <-- this has proven to work, and so is ActiveClass

class Car:public ActiveClass
{
private:
	bool state;						// suspended or resumed
	double speed;					// speed of the vehicle
	string label;					// label of the vehicle
	
public:
	Car(bool s_input=TRUE, double vi = 0.0, string name = "This car");		// constructor
	void accelerate();								// accelerate by 1 kph/s
	void cruise(double cruise_speed);				// cruise control
	double v_get() const;							// speed accessor
	bool s_get() const;								// state accessor
	string l_get() const;							// label accessor
	int main(void *args);							// main function
};

Car.cpp

Code:

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

Car::Car(bool s_input, double vi, string name)
{
	// store state, speed and label of vehicle
	state = s_input;
	speed = vi;
	label = name;

	// deal with suspending or resuming the vehicle initially
	if(state)				// Suspend
	{
		Suspend();
	}
	else					// Resume
	{
		Resume();
	}
}

void Car::accelerate()
{
	speed++;
}

void Car::cruise(double cruise_speed)
{
	speed = cruise_speed;
}

double Car::v_get() const
{
	return speed;
}

bool Car::s_get() const
{
	return state;
}

string Car::l_get() const
{
	return label;
}

int Car::main(void *args)
{
	string state_output;
	if(s_get())				// Suspend
	{
		state_output = "suspended";
	}
	else					// Resume
	{
		state_output = "running";
	}

	while(1)
	{
		system("cls");

		cout << l_get() << " is " << state_output << " and travelling at " << v_get() << " kph \n";

		SLEEP(200);
	}
	return 0;
}

driver.cpp:

Code:

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

int main(void)
{
	/*Car Impala = new Car(FALSE, 23.0, "Impala");
	Car NineOneOne = new Car(TRUE, 0, "911");
	Car ThisCar = new Car;*/

	Car Impala(FALSE, 23.0, "Impala");
	Car NineOneOne(TRUE, 0.0, "911");
	Car ThisCar;

	Impala.WaitForThread() ;
	NineOneOne.WaitForThread() ;
	ThisCar.WaitForThread() ;

	cout << "Finished" << endl;

	return 0;
}

I have tried both methods in the driver (non-commented out portion and commented out code) to instantiate three objects. However, I have gotten a compiler error with the commented out code like below in Microsoft Visual C++ 6.0:

--------------------Configuration: car - Win32 Debug--------------------
Compiling...
driver.cpp
I:\Current Courses\EECE 314\projects\car\driver.cpp(15) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(15) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(15) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(15) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(15) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(15) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(15) : warning C4800: 'class Car *' : forcing value to bool 'true' or 'false' (performance warning)
I:\Current Courses\EECE 314\projects\car\driver.cpp(16) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(16) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(16) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(16) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(16) : warning C4800: 'class Car *' : forcing value to bool 'true' or 'false' (performance warning)
I:\Current Courses\EECE 314\projects\car\driver.cpp(17) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(17) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(17) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(17) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(17) : warning C4800: 'class Car *' : forcing value to bool 'true' or 'false' (performance warning)
Error executing cl.exe.

car.exe - 7 error(s), 10 warning(s)

and with the non-commented code:

--------------------Configuration: car - Win32 Debug--------------------
Compiling...
driver.cpp
I:\Current Courses\EECE 314\projects\car\driver.cpp(19) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(19) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(19) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(19) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(20) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(20) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
I:\Current Courses\EECE 314\projects\car\driver.cpp(21) : error C2259: 'Car' : cannot instantiate abstract class due to following members:
i:\current courses\eece 314\projects\car\car.h(9) : see declaration of 'Car'
I:\Current Courses\EECE 314\projects\car\driver.cpp(21) : warning C4259: 'int __thiscall ActiveClass::main(void)' : pure virtual function was not defined
i:\current courses\eece 314\projects\car\rt.h(477) : see declaration of 'main'
Error executing cl.exe.

car.exe - 4 error(s), 4 warning(s)

I'm getting quite lost with the signature when instantiating the class objects. Any suggestions?

new is for pointers, not regular objects, so that's why the commented out part doesn't work.

Because it's less ambiguous. For C++ it's not a big deal, but for C

Code:

int main(void)

is different than

Code:

int main()

And adding void to empty parameter lists has nothing to do with Microsoft. Pretty much any C++ programmer coming from a C background will do it. And apparently you do it too if your sig is to be trusted.

Originally Posted by cpjust

new is for pointers, not regular objects, so that's why the commented out part doesn't work.

I actually tried the object instantiation and dynamic memory allocation methods, but both of them don't work either.

It's a hard big deal trying to debug a so long list of errors.
You might break your code and debug it step by step, compiling little pieces.
Did you write the code you posted and then compiled it all in one time?
If so, I'd say it's a bad way to work, expecially if you are not really expert.

Personally, I'm not expert and neither a newbie, but I'd had compiled a code like yours at least 20 times, even more.

Well, I initially had nothing in my driver .cpp file and my Car class compiled with no complaints. The error happened right after I instantiate the class.

I actually found the problem now. Thanks for your help.

Please tell us so :P