deleting class array

[Allanon]

Hi, I've been able to create an array of class variables, but I can't get the program to delete them without an access violation.
Thanks!

class TEST
{
  public:
    TEST(int y);
    int x;
};

TEST::TEST(int y)
{
  x=y;
}

class TEST2
{
  public:
    TEST *test[];
};

void main()
{
  TEST2 t2;
  for(int i=0; i<6;i++)
    t2.test[i] = new(TEST)(i); // creating

  // delete them here

} 

[amac]

What exactly are you tring to do?


I guess you would just do something like this:

for(i = 0; i < 6; i++)
    delete t2.test[i];

Normally class members are destroyed in the classes Destructor... It is automatically called by 'delete'

class TEST
{
public:
    TEST(void);
    // This is the destructor.
    ~TEST(void);
};

TEST::~TEST(void)
{
    for(int i = 0; i < 6; i++)
        delete this->test[i];

}

[CornedBee]

Where the deletion is doesn't matter. And since the array is a member of TEST2 it certainly won't be in the TEST destructor.

But the core deletion code should work.

[Allanon]

It still is giving an access violation when it tries to delete the pointer.

TEST2::~TEST2()
{
  for(int i=0; i<6;i++)
    delete test[i]; 
} 

I've tried how many different sorts of combinations with delete but whatever I try it keeps having an access violation.

[CornedBee]

Oh, and did I mention that [] is bad to use here anyway? This array has no lenght. You may not access it's elements because it has none. Declare test as
TEST *test[6];

[Allanon]

I can't place
TEST *test[6];
because I want it to be a dynamic array, thats whats been giving me problems, I figured you would just start with
TEST *test[]; but trying to delete it won't work, so I don't know how to have the dynamic array and still delete it

[CornedBee]

Then I suggest you don't use an array of pointers but rather one pointer and use array new:

TEST *ar;
ar = new TEST[6](1);
// ...
delete[] ar;

Note that you can't pass individual arguments to the constructors anymore, only the same to each constructor. But this syntax is far easier to use. Else you'd have to use:

TEST **ar;
ar = new TEST*[6];
for(int i=0;i<6;++i)
  ar[i] = new TEST(i);
// Access:
ar[3]->DoSomething();
// Deletion:
for(int i=0;i<6;++i)
  delete ar[i];
delete[] ar;

Quite bad, and terribly prone to memory leaks.

[Allanon]

what I've meant is instead of allocating 6 I want that to be a variable that gets increased everytime I call a function of mine. I've been able to get it to work with a fixed amount to begin with, but not when its a variable

[kedaman]

you can allocate a variable amount of objects with new

[CornedBee]

But if that amount changes you have to reallocate the memory every time. In that case you should rather use a vector:

#include <vector>
using std::vector;

typedef vector<TEST> testvec;

testvec array;
// add a new element:
array.push_back(TEST(4));

No deletion needed, the vector does it all for you.

[Allanon]

that works much better thank you! is there any tutorial that shows more about the vector, like how to go about shrinking the vector array and swapping values

[CornedBee]

I don't know if there is a tutorial for vectors, but a good reference should suffice. Look up vector in MSDN or on SGI's reference page.