Finding size of dynamically allocated array

Question

Why is it not possible to get the length of a buffer allocated in this fashion.

AType * pArr = new AType[nVariable];

When the same array is

Answer 1

There is no portable way in C++ to get the size of a dynamically allocated array from the raw pointer.

Under MSVC and WIN32 you can get the size of the allocated block with the _msize(void*) function.

see https://msdn.microsoft.com/en-us/library/z2s077bc.aspx for further details.