is it possible to get memory block size allocated by 'new'?

Question

Hello i need to record my heap, but now i am just thinking to overload 'new' operator with my function.

I need to summary the real count bytes of memory that was increased after malloc() or Heap*() or other windows mem* functions

But for now i need to analyze current heap implementation. Is it possible to get blocks size like allocated by HeapAlloc() function - HeapSize()?

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Answer 1

I can see that you did not search the documentation.

HeapSize() exists.

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Edit On reflection, perhaps you were asking for an alternative to HeapSize() that you can use when you performed allocation yourself with new .

The answer is no. The standard allocation routines don't have anything to grab information about the memory block, because:

• That's highly implementation-dependent, and
• You already know the block size (because you specified it in the first place), so what would be the point of the bloat?

In fact HeapSize() is the implementation-dependent function for Windows that does this, but you can only use it when you performed a HeapAlloc() .

There's [also non-standard] _msize that can be used with malloc and friends, but new may not use malloc .

Therefore I suggest that you just track the sizes yourself in your allocator.

Answer 2

_msize

According to the documentation it works for calloc,malloc and realloc .

However, at least under Visual Studio, using the default allocator, it works also for new .

It is not a good idea to use it, however, it may do the work for your analysis.

One more thing:

External tools such as VMMap may help for such analysis.