Vfrdtyky

So here's my template class declaration:

template <class elemType>

class listType

I have a constructor like this:

listType(const elemType &, const elemType &, const elemType &, 

const elemType &, const elemType &){



list[0] = a;

list[1] = b;

list[2] = c;

list[3] = d;

list[4] = e;



}

With a protected member variable like this:

elemType *list;

This is to pass in objects of type stockType in my code. I inherited a class from this template class listType called stockListType and tried to make a constructor that would pass in the parameters to the already made constructor in listType with this:

stockListType :: stockListType(const stockType &a, const 

stockType &b, const stockType &c, const stockType &d, const 

stockType &e) : listType(a, b, c, d, e) {



}

I'm not sure if I understand how to use class templates and constructors with class templates that I inherited a class from.

I tried making 5 objects of type stockType (inputting their information for their member variables using a file) and then trying to use the constructor of the inherited class with those objects in my main code:

stockListType object(obj1, obj2, obj3, obj4, obj5); 

But I keep getting an error when it tries to run.

EDIT:
The error I get is Thread 1: EXC_BAD_ACCESS (code=1, address=0x0)

The child class header is:

#ifndef stockListTypeHeader_h

#define stockListTypeHeader_h



#include "listType Header.h"



class stockListType : public listType <class stockType>

{

public:

stockListType(const stockType &, const stockType &, const stockType &, const 

stockType &, const stockType &);



void sortList();

void swap(stockType&, stockType&);



const void printList();



protected:

    stockType *sortIndicesGainLoss;









};





#endif /* stockListTypeHeader_h */

And the .cpp file of the child class is:

#include <stdio.h>

#include "stockListTypeHeader.h"

#include "stockType.h"

#include <iostream>





void stockListType:: sortList(){

    sortIndicesGainLoss = list;



for(int i =0; i<5; i++){

    for(int j =0; j<5-i-1; j++) {

        if (sortIndicesGainLoss[j].getStockSymbol() > 

sortIndicesGainLoss[j+1].getStockSymbol()){

            swap(sortIndicesGainLoss[j], sortIndicesGainLoss[j+1] );

        }

        }

    }

}



void stockListType:: swap(stockType &xp, stockType &yp){

stockType temp = xp;

xp = yp;

yp = temp;



}



 void const stockListType:: printList() {

     for(int i=0; i<5; i++)

         cout << sortIndicesGainLoss[i];



}



 stockListType :: stockListType(const stockType &a, const stockType &b, const 

stockType &c, const stockType &d, const stockType &e) : listType(a, b, c, d, e) 

{



}

EDIT 3:

Thank you all for helping me, I figured out it was because I hadn't initialized list or my sortIndicesGainLoss.

Now I am getting an error under my sortList method. Does anybody have a clue as to why?

elemType *list; is not initialized. I really think that's the problem right there. try initializing it in the constructor to something like

list = new elemType [5]; since you'll be using 5 elements.

listType(const elemType &, const elemType &, const elemType &, 

const elemType &, const elemType &){



    this->list = new elemType [5];



    list[0] = a;

    list[1] = b;

    list[2] = c;

    list[3] = d;

    list[4] = e;



}

The problem is, in the constructor of listType you are not allocating memory for the array list. If your class has a member of type * elemType, this would be a pointer to a elemType, but it does not mean it points to allocated memory.
A solution to your problem is to write the constructor of listType as follows:

listType(const elemType &, const elemType &, const elemType &, 

const elemType &, const elemType &) : list(new elemType[5]) {



list[0] = a;

list[1] = b;

list[2] = c;

list[3] = d;

list[4] = e;



}

But then do not forget to deallocate list when your object gets destructed. You need a distructor inside the definition of the class list as:

virtual ~listType { delete list; }

The destructor should be virtual, see the discussion here

That said, rather than using C-style arrays, if the size of the array list is known at compile time, I would rather suggest to use the C++11 arrays. So, in the declaration of the class listType your protected member list should be declared as

std::array<elemType, 5> list;

Then you do not need anymore to allocate and deallocate "manually" the array list. Also, you need to #include <array>

As for the second error when sortIndicesGainLoss = list;: you do not need the member stockType *sortIndicesGainLoss. In fact, by calling the constructor of the base class listType, you have already initialized the array list of elemType, which, being protected, is accessible to stockListType. So to solve the problem:

• Remove stockType *sortIndicesGainLoss from the declaration of stockListType




• In the cpp file remove sortIndicesGainLoss = list;, and everywhere use the inherited member list instead of sortIndicesGainLoss