Should new/new[] match delete/delete[]?

Question

I knew that when we allocate memory by using new/new[], then we should release the memory by using the delete/delete[] respectively.

Here is the question,

Ca

Answer 1

I guess that you are not satisfied with anything but a reference to the standard, so here it is.

You can find it under 3.7.3.2 in the Standard for C++03.

3 The value of the first argument supplied to one of the deallocation functions provided in the standard library may be a null pointer value; if so, the call to the deallocation function has no effect. Otherwise, the value supplied to operator delete(void*) in the standard library shall be one of the values returned by a previous invocation of either operator new(size_t) or operator new(size_t, const std::nothrow_t&) in the standard library, and the value supplied to operator delete[] (void*) in the standard library shall be one of the values returned by a previous invocation of either operator new[] (size_t) or operator new[] (size_t, const std::nothrow_t&) in the standard library.

So the answer to your question is no.

Answer 2

Can I use delete[] to release the memory allocated by new?

Yes you could, but you will be sorry if you do.

Answer 3

No, you should match the non-array form of new with non-array delete, and likewise for the array forms.

See the C++ FAQ Lite section on Freestore Management

This is especially good: http://www.parashift.com/c%2B%2B-faq-lite/freestore-mgmt.html#faq-16.12

[16.12] What if I forget the [] when deleteing array allocated via new T[n]?

All life comes to a catastrophic end.

It is the programmer's —not the compiler's— responsibility to get the connection between new T[n] and delete[] p correct. If you get it wrong, neither a compile-time nor a run-time error message will be generated by the compiler. Heap corruption is a likely result. Or worse. Your program will probably die.