使用delete []和new（放置）运算符的Visual C ++堆损坏错误

Question

Code snippet:

#include <new>
char buffer[512];

int main()
{
   double *pd;
   pd = new (buffer) double[5];
   delete [] pd;
   return 0;
}

This only hangs when using the placement new form of the new operator.

I'm using the following tools and options:

> cl -EHsc foobar.cpp
Microsoft (R) C/C++ Optimizing Compiler Version 18.00.21005
Microsoft (R) Incremental Linker Version 12.00.21005.1

Answer 1

pd = new (buffer) double[5];

What you are doing there is reusing the memory that buffer occupied to create an array of double. So now you are deleting a memory that you didn't not allocate with new .

Answer 2

Don't do that. The program didn't allocate the memory with operator new or operator new[] , so shouldn't delete it.

Answer 3

You did not allocate that memory, so you should not try to free it (with delete [] ).

In general, you would run the destructors:

for( i = 0; i < 5; i++ ) {
    T* p = pd + i;
    p->~T();
}

But for double that isn't necessary.