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vsnadagouda@gmail.com · Guest

Hello All,

I am sort of lost while creating and deleting objects. Please take a
look at the small piece of code below:
============================================================================
#include <iostream>

using namespace std;

class Validator
{
public:
Validator ()
{
cout << "In Validator::Validator() " << endl;
}
void display ()
{
cout << "In Validator::display()" << endl;
}
virtual ~Validator ()
{
cout << "In Validator::~Validator() " << endl;
}
};

class Mars: public Validator
{
public:
Mars ()
{
cout << "In Mars::Mars() " << endl;
}
void display ()
{
cout << "In Mars::display()" << endl;
}
~Mars ()
{
cout << "In Mars::~Mars() " << endl;
}
};

class Safe
{
public:
Validator *ptr[2];
// Validator **ptr; // THIS DOESNT WORK
Safe ()
{
cout << "In Safe::Safe() " << endl;
}
void display()
{
cout << "In Safe::display() " << endl;
}
~Safe ()
{
cout << "In Safe::~Safe() " << endl;
}
};

int main ()
{
Safe *safe_ptr = new Safe();
safe_ptr->ptr[0]= new Mars();
safe_ptr->ptr[1]= new Mars();
delete safe_ptr->ptr[0];
delete safe_ptr->ptr[1];
//delete []safe_ptr->ptr; //THIS ALSO DOESNT WORK
delete safe_ptr;
}
============================================================================

I have Safe class, which will have pointers to Validator/Mars objects.
The number of objects of Validator/Mars is decided at the run time.

Above piece of code assumes that there will 2 objects of type
Mars/Validator (by explicitly mentioning Validator *ptr[2] ). But when
I try to make it general like "Validator **ptr" it doesn't work.

Also while deleting I used delete []safe_ptr->ptr to delete all the
objects created, but the destrucor is never called. ut when I call like
delete safe_ptr->ptr[0];
delete safe_ptr->ptr[1];
it works.

Can someone help in how to make this program generic.

Thanks in advance
-Vallabha

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Victor Bazarov · Guest

[email]vsnadagouda (AT) gmail (DOT) com[/email] wrote:

alexey.br@gmail.com · Guest

class Safe
{
public:
Validator **ptr; // NOW THIS DOES WORK

.......
int main()
{
Safe *safe_ptr = new Safe();
typedef Validator* PValidator;
safe_ptr->ptr = new PValidator[2]; // ! allocate memory for array of
pointers or simply use std::vector<PValidator> or even with smart
pointers.
safe_ptr->ptr[0]= new Mars();
safe_ptr->ptr[1]= new Mars();
delete safe_ptr->ptr[0];
delete safe_ptr->ptr[1];
delete[] safe_ptr->ptr; // now u need to delete this
array
delete safe_ptr;
return 0;
}

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apolly · Guest

As you create objects by new not new[], you must destroy them by delete
but not delete[]. It is also important to remember : NEVER treat arrays
polymorphically. Check More Effective C++ Item3 to find out the detail.

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mlimber · Guest

[email]vsnadagouda (AT) gmail (DOT) com[/email] wrote:
[snip]