Pointer Deletion Crash

Question

Edit:

I've implemented copy constructors (both from the suggested answer). I have done this in my controller class, as well as equivalent versions in it's sub classes. However, this has not resolved the issue. Also, a counter and console comment in the removePawn() function (the only place in the program that delete is called) shows that it is only called once.

In more detail, there is one instance of each subclass (not pointers). These are declared in my world class. Both are used as parameters in the same world classes methods via the baseController class pointers. The problem is, while both are going through the same processes in the same order, if one class has removePawn() called on it, the program is fine and will run continually. However if the second class has removePawn() (delete specifically) called on it, it crashes the program at that instruction.

I've also checked the addresses. The address of the pointer just after allocation is identical to the address at the point of deletion.

More info: I will get a segmentation error when closing the program ONLY if the player is killed (deleted then given a new pawn). However, if the program is started then closed without any more than the first new and last delete, then it runs perfectly fine.

Original:

I'm having a bit of trouble with pointers. I understand them and believe my code is fairly robust however I seem to get a complete crash while calling this section of code.

Pawn is a basePawn* initialized to NULL.

if (pawn != NULL)
{
    cout << "Calling delete.\n";
    delete pawn;
    pawn = NULL;
}

This is a university assignment for a PS2 program so my debugging is limited to basic printing to the console.

Removing the delete line allows the main new/delete section to run a few times however it eventually crashes too (I assume this is because the memory limit is reached however I can't be sure)

I have checked all the usual culprits, the pointer is initialized to null and only deleted once (new is always called also).

I may be making a fairly obvious mistake however I have no clue. Any suggestions would be great. (I can post up more code if needed).

Edit:

Here's how the structure of the code works.

basePawn is a class with some fairly basic methods representing the character.

Controller is a class with a pointer to a basePawn (initially set to NULL) used as the brain of the character (AI or player controlled). It contains a removePawn method.

void controller::removePawn()
{
    if (pawn != NULL)
    {
        cout << "Calling delete.\n";
        delete pawn;
        pawn = NULL;
    }
}

This method gets called in the destructor. It also gets called when the pawn is removed from the level.

It also has a respawn method.

if (pawn == NULL)
{
    respawnCounter++;

    if (respawnCounter >= respawnTime)
    {
        //Switch block to change class
        pawn = new basePawn;

        if (pawn !=NULL)
        {
            pawn->boardY = 4; //Will be random
            pawn->boardX = 5; //Will be random

            respawnCounter = 0;

            pawn->setIdle();

            return true;
        }
    }
}

Edit:

baseController header file

#ifndef _BASEPAWNCONTROLLER_H
#define _BASEPAWNCONTROLLER_H

#include "basePawn.h"
#include "textureManager.h"
#include "direction.h"
#include "vector2f.h"

//Used to control pawns
//Allows the same commands to be used to control different pawns
class basePawnController
{
private:
protected:
basePawn *pawn;

int respawnCounter,
    respawnTime;

vector2f    targetDest;

bool        bMoving,
            bTarget;

void        removePawn();

public:

bool    bFirstFrameDead;

basePawnController();
virtual ~basePawnController();

virtual void update();

basePawn *getPawn();
void setPawn(basePawn *p);  
void setTarget(float x, float y);
direction getDir();
bool isMoving();
bool hasTarget();

virtual bool respawn();
virtual void render(textureManager &tManager);

virtual bool wantsPawn();
virtual void giveTargetInfo(direction d, int n);
};

#endif

Answer 1

Well, you guys were pretty much right.

After adding the copy constructor and assignment operator, I performed more checks to see where my problems were actually occurring. Turns out it wasn't anything to do with my controller classes directly, but my pawn and world classes.

My pawn has a vector of damageNode* which I wasn't deleting. Not a big issue as I had a pointer to them in the world. But I never deleted them in the world class either, hence I was getting seg faults when removing the pawn and the world.