Dynamically Expanding an Array

Consider the following:

Code:

---

int *p;
p = new int[5];
for(int i=0;i<5;i++)
  *(p+i)=i;

---

Now suppose we want to add a 6th element (without using vector)

One way is to copy it across to a larger array:

Code:

---

int *p;
p = new int[5];
for(int i=0;i<5;i++)
  *(p+i)=i;

// realloc
int* temp = new int[6];
std::copy(p, p + 5, temp);
delete [] p;
p = temp;

---

This looks like a very expensive operation and im looking for other ways.

Three questions regarding the above:

1. Not using vector, is this the best way to do this?
2. What about using realloc? How would I use realloc in this situation?
3. Any other ways apart from realloc or vector?

if you were talking about objects that do a lot of work in their (copy) constructors, or that contain a lot of member data (large buffers, etc.), I'd agree that it would be pretty expensive, but int is not a type that is especially expensive to copy.


to answer your questions:
1. yes.
2. don't use calloc/malloc/realloc/free in a C++ program, as there is no guarantee that it will cooperate properly with other things using new/delete.
3. I can't think of any that are better than what you've got there.