/*
	testArrayOfPointers.cpp
	John Sterling
	CS1124

	What if we have a class with no default constructor?
	How can we create an array of objects?
*/

#include <string>
#include <iostream>
using namespace std;

// Here is a simple Person class.
// It defines a constructor that takes two arguments, but no
// default constructor.  Note that default constructors are provided 
// automatically, but only when no other constructor is provided.
class Person {
public:
	Person(const string& fn, const string& ln) : first(fn), last(ln) {}
	void display() const {cout << first << ' ' << last << endl;}
private:
	string first, last;
};

int main() {

	// We wish to have an array of people so we try:
	Person arrOfPeople[10];			// COMPILATION ERROR
	// There wasn't any Person default constructor, so this
	// didn't work.

	// Second approach is an array of pointers to people.
	Person* arrOfPeoplePtr[10];		// This works!
	// Initialize the pointers to NULL.
	for (int i = 0; i < 10; i++) arrOfPeoplePtr[i] = NULL;

	// But we would really like to use a dynamic array, because we may
	// need to resize later.

	// Third approach is a dynamic array of people.
	Person* dynamicArrayOfPeople = new Person[10];		// COMPILATION ERROR
	// This fails to work, for the same reason as the first appproach.

	// Fourth approach is a dynamic array of pointers to people.
	// How do we declare such a beast?
	Person** dynamicArrayOfPeoplePtr = new Person*[10];
	// Initialize the entries to NULL.
	for (int i = 0; i < 10; i++) dynamicArrayOfPeoplePtr[i] = NULL;
	// Put one item into the array.
	dynamicArrayOfPeoplePtr[0] = new Person("Marilyn", "Monroe");
	// Display it.
	dynamicArrayOfPeoplePtr[0]->display();

	// Finally we want to free up all the people that have been 
	// allocated for this array and the array itself.  If we only
	// delete the array, then we will have a memory leak, all those
	// people we created on the heap.
	// So first we loop through the array deleting everyone.
	// Note that some of the entries in the array are still NULL
	// but that's ok, because deleting a NULL pointer doesn't do
	// anything.
	for (int i = 0; i < 10; i++) delete dynamicArrayOfPeoplePtr[i];

	// Finally we can delete the array itself.
	delete [] dynamicArrayOfPeoplePtr;

	// It might be good to set the array pointer to NULL.
	dynamicArrayOfPeoplePtr = NULL;


}