Differences between using realloc vs. free -> malloc functions

Question

Why would one use realloc() function to resize an dynamically allocated array rather than using free() function before calling the malloc() function again (i.e. pros and con

Answer 1

Well, realloc may change the size of the block in place, or allocate a new one and copy as much as will fit. In contrast, malloc and free together can only allocate a new one, and you have to do your own copying.

To be frank, realloc doesn't get as much use these days because it doesn't work well with C++. As a result, there's been a tendency for memory managers not to optimize for it.