Meaning c plus plus pointer to an array and pointer to a structure?

They both mean the same thing; an array is a type of data structure (a linear structure). A pointer variable is just a variable like any other, but one that is used to specifically store a memory address. That memory address may contain a primitive data type, an array or other data structure, an object or a function. The type of the pointer determines how the data being pointed at is to be treated. Pointers must always be initialised before they are accessed, and those that are not specifically pointing at any reference should always be zeroed or nullified with the NULL value. This ensures that any non-NULL pointer is pointing at something valid. Remember that pointer variables are no different to any other variable insofar as they occupy memory of their own, and can therefore point to other pointer variables.