Question on void*__Crun::vector_new function

Question

Hi,
This is using Studio 11 on x86. I am trying to allocate a array of class using
MyObject* objs = new MyObject[size];
I notice that this call occasionally ends up calling the destructor of MyObject. The size could potentially be very large. Is it possible that if the allocation fails, vector_new might cleanup any already allocated MyObject class by calling the destructor?

Answer 1

This question is about C++, and should be posted in the C++ forum.
When you write
MyObject* objs = new MyObject[size];the compiler generates code to invoke the MyObject constructor for each element of the vector. The compiler generates a call to a helper function in the C++ runtime library to do the initialization.
The destructor for a heap object like this is never invoked automatically. You have to write code to call the destructor, either an explicit call like this:
objs[0].~MyObject()or by deleting the array:
delete [] objs;In this case, the destructor is called for each object in the array.
Are you saying that you see the MyObject destructor invoked while processing the new-expression? I don't see how that can happen, unless you have a wild jump due to errors in the code.
For example, if the MyObject constructor winds up using an invalid pointer, or writing outside the bounds of the current object, it can corrupt memory, leading to seemingly random behavior. Running the code under the debugger with Run Time Checking enabled will find many such errors.
Run-Time Checking is only partially supported on x86 using Studio 11. Sun Studio 12 provides full support. To use RTC:
% dbx myprog
(dbx) check -all
(dbx) run