Overloading new

[Arta]

Is it possible to overload new at global scope and still call the original new from within that function?

Something like:

Code Select Expand


void *operator new(size_t Size)
{
   void *Ptr = ::operator new(Size);

   if(!Ptr)
   {
      // Memory allocation failed
      Output(MSG_FATAL, "Insufficient memory!\n");

      ExitProcess(0);
   }

   return Ptr;
}


...except that doesn't recurse.

[Eibro]

What are you trying to do? Provide extra handling if allocation fails? If so, see std::set_new_handler().

[Arta]

Ah, excellent. Thanks.

[Skywing]

I'd use something else, like malloc or HeapAlloc.  No scoping tricks needed there.

You could also use the throwing new with exception handlers, as a possible alternative to set_new_handler if this fits your program better.

[Arta]

is it safe to delete memory allocated with malloc? Pretty sure it is, but would like to confirm

[Yoni]

is it safe to delete memory allocated with malloc? Pretty sure it is, but would like to confirm

No
Standard C++ says you can't mix them.

Maybe you can in specific compilers as an extension.

[iago]

I still remember a classic:

HashTable::~HashTable()
{
 delete table;
 free(position);
}

.. or something very similar to that.  It was about there that we scrapped it and started over

[Skywing]

is it safe to delete memory allocated with malloc? Pretty sure it is, but would like to confirm

No.  It's also not safe to delete memory allocated with new[].  Note that this is even true with VC - usually, if you mix the two, you'll cause heap corruption (at best) or crash immediately (at worst).

If you are overloading operator new, you should probably also overload operator delete.

[Arta]

In which case, my original question stands. How do I avoid the scoping issue? Just curious now