C++ 面试问题准备4

Memory Allocation/Deallocation

What is the difference between new/delete and malloc/free?
What is difference between new and malloc?

What is the difference between delete and delete[]?

What is difference between malloc()/free() and new/delete?
What is the difference between "new" and "operator new" ?
What is Memory alignment??

Is there a way to force new to allocate memory from a specific memory area?
How does free know the size of memory to be deleted.?
Can I free() pointers allocated with new? Can I delete pointers allocated with malloc()?
Why should I use new instead of trustworthy old malloc()?

Can I use realloc() on pointers allocated via new?
Do I need to check for NULL after p = new Fred()?
Do I need to check for NULL before delete p?
What are the two steps that happen when I say delete p?
In p = new Fred(), does the Fred memory "leak" if the Fred constructor throws an exception?

How do I allocate / unallocate an array of things?

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

Can I drop the [] when deleteing array of some built-in type (char, int, etc)?

After p = new Fred[n], how does the compiler know there are n objects to be destructed
during delete[] p?
After p = new Fred[n], how does the compiler know there are n objects to be destructed
during delete[] p?

In p = new Fred(), does the Fred memory "leak" if the Fred constructor throws an exception?