Pointers Issues

Technical C/C++
1

Hey everyone,

So, we are having issues with pointers. I just wanted to know if anyone else is getting the same errors. They are kernel task exceptions. When I get rid of the pointers and initialize the classes another way, it all works.

If anyone has a solution, please tell me. Otherwise, I just want to know if everyone else is having the same issue or it’s just me…


#include "WPILib.h"
#include "Drive.h"

class RobotDemo : public SimpleRobot
{
	Drive *dr;

public:
	RobotDemo(void)
	{
		GetWatchdog().Kill();
		dr = new Drive();
		//AxisCamera &camera = AxisCamera::GetInstance();
		dr->myRobot->SetExpiration(0.1);
	}

	/**
	 * Drive left & right motors for 2 seconds then stop
	 */
	void Autonomous(void)
	{
		GetWatchdog().Kill();
		//dr->myRobot->SetSafetyEnabled(false);
		dr->myRobot->Drive(0.5, 0.0); 	// drive forwards half speed
		Wait(2.0); 				//    for 2 seconds
		dr->myRobot->Drive(0.0, 0.0); 	// stop robot
	}



	void OperatorControl(void)
	{
		GetWatchdog().Kill();
		//dr->myRobot->SetSafetyEnabled(true);
		while (IsOperatorControl())
		{
			printf("In Operator
");
			dr->myRobot->TankDrive(dr->leftstick, dr->rightstick);
			Wait(0.01);
		}
	}

	void Disabled(void)
	{
		printf("Disabled
");
	}
};

START_ROBOT_CLASS(RobotDemo);

It keeps giving me that the Drive *dr; has not been initialized correctly, where I believe I have. Anyone know any ways I can debug this?

Thanks,
-Eagle Engineering 1138

2

If you suspect you have a problem with your code, you need to post it so other people can help you.

3

Just posted the code in the main post.

4

Is there indeed a Drive() constructor with no parameters?

5

No, I have a separate Drive class.

Drive.h



#ifndef DRIVE_H_
#define DRIVE_H_
#include "WPILib.h"

class Drive
{
public:
	Drive();
	
	RobotDrive *myRobot;
	
	Jaguar *leftmotor;
	Jaguar *rightmotor;
	
	Joystick *leftstick;
	Joystick *rightstick;
};

#endif

Drive.cpp



#include "WPILib.h"
#include "Drive.h"

Drive::Drive()
{
	printf("Initializing Drive.cpp
");
	
	leftmotor = new Jaguar(1);
	rightmotor = new Jaguar(2);
	
	myRobot = new RobotDrive(leftmotor, rightmotor);
	
	leftstick = new Joystick(1);
	rightstick = new Joystick(2);
};

There is the header file and the cpp file.
MyRobot is in the main post.

6

Another way? What way works? Do you know which line kills it?

7

I seem to remember something about needing to initialize things in the same order they were defined. This is just a guess, but have you tried moving the


myRobot = new RobotDrive(leftmotor, rightmotor);

line to the very beginning of Drive::Drive()?

8