CODEWITHSUNDEEP
c++arraysdestructor
hello
hello

Reputation: 1228

Multiple delete in destructor

If I have two dynamic arrays as private data members:

std::string* first_array;
std::string* second_array;

I know I can simply delete like this in the destructor

myClass::~myClass()
{
   delete[] first_array;
   delete[] second_array;
}

The concern I have is this, not all the time do I have data inside both array, so is something like this considered best practice ?

myClass::~myClass()
{
   if(first_array)
       delete[] first_array;
   if(second_array)
       delete[] second_array;
}

I tried both and it both worked, not sure which one is better in terms of performance.

Upvotes: 0

Views: 294

Answers (2)

Nicholas Smith
Nicholas Smith

Reputation: 1005

Deleting a pointer that may be NULL is perfectly ok. As already stated by others, calling delete on a NULL pointer results in a NOP.

However, after deleting any pointer, no matter where, why, how, or when, you should assign the pointer to NULL immediately afterwards. Failing to do this can lead to accidental double-deletion of the pointer, which is catastrophically bad for your program (https://isocpp.org/wiki/faq/freestore-mgmt#double-delete-disaster).

For the same reason that you would not initialize a pointer to some random address, you do not want to leave your pointer dangling in the wind after deleting it, just waiting to be the bullet in your foot.

Upvotes: 0

Captain Obvlious
Captain Obvlious

Reputation: 20063

The C++ Standard specifies calling delete on a null pointer value will result in a NOP (No-Operation). It is perfectly valid, acceptable, and generally preferred.

Upvotes: 6

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