重新分配后删除C ++中的数组指针是否安全？

Question

Suppose I'd like to swap two array pointers in C++ which I have allocated with new [] and different length. Is it safe to delete [] them after swapping? What if they have the same length?

int *a;
int *b;
int *tmp;

a = new int[5];
b = new int[10];
tmp = a;
a = b;
b = tmp;

delete [] a;
delete [] b;

Answer 1

Is it safe to delete [] them after swapping?

Yes.

What if they have the same length?

The length is irrelevant.

Answer 2

Yeah, you can. The reason being is that the information needed to accurately free up that memory is managed by the free store (the heap in most cases). So it knows how to delete based on address rather than variable. Often times this information is held in *(ptr - x) where x is the size of the tracking data.

Answer 3

Yes, you can surely delete the pointer once your swapping is done. As you no longer need to point your array so in that case, it is safe to delete after swapping.

int *a;
int *b;
int *tmp;

a = new int[5];
b = new int[10];
tmp = a;
a = b;
b = tmp;

delete [] a;
delete [] b;

And this is the correct way of doing it. Great Job