[acqq]

I'd expect that such growth seldom allows the realloc to remain in-place (unless it's the last thing allocated before and already in a big preallocated chunk of the allocator)? Have you observed what you then get in your program? Which allocator is used underneath?

[cperciva]

I haven't looked. I use whatever allocator is in libc anyway, so it will depend on what platform you're running on.

At worst, using realloc produces the same results as malloc/memcpy/free. At best, it might save a memcpy. No harm in giving it that flexibility.