Why does scanf() need & operator (address-of) in some cases, and not others?

Question

Why do we need to put a & operator in scanf() for storing values in an integer array but not while storing a string in a char array?

Answer 1

Because characters arrays are already pointers.

You can think of C arrays as pointers to a stack-allocated amount of RAM. You can even use pointer operations on them instead of array indexing. *a and a[0] both produce the same result (returning the first character in the array).