In C we used malloc(), free(), but in C++ youare using new, delete, but in C we also have realloc, which will alloc the new block and
Let's see what Bjarne Stroustrup thinks!
If you want to, you can of course use realloc(). However, realloc() is only guaranteed to work on arrays allocated by malloc() (and similar functions) containing objects without user-defined copy constructors. Also, please remember that contrary to naive expectations, realloc() occasionally does copy its argument array.
In C++, a better way of dealing with reallocation is to use a standard library container, such as vector, and let it grow naturally.