// showing how to pass and return pointers to objects
// as well as arrays of object pointers
// RPF  2/8/01 -- for COM1101, Labs 5 & 6


#include <iostream>
using namespace std;

// c is a trivial class with one member variable
class c {
public:
	int n;
};

void passPtr(c *cArg); // prototype, argument is pointer to a c

void passPtr(c *cArg) {} // definition with empty body

void passPtrArr(c *cArrArg[]); // prototype, argument is array of pointers to c

void passPtrArr(c *cArrArg[]){} // definition with empty body

c* returnPtr(c *cArrArg[]); // prototype, returns ptr to one c object

c* returnPtr(c *cArrArg[]){
	cArrArg[2]->n = 55; // sets member var n of 2nd element to 55
	return cArrArg[2]; // returns value of the array el. 2 which is a pointer
}

void changeAnObj(c *cObjPtr); // pass an object via pointer and change it

// The pointer is passed and a value within the object is changed.
// When the function is finished, the object pointed to has been changed
// internally, even though the pointer hasn't -- the object is still at
// the same region in memory. Just one of the values stored in that region
// has been changed.

void changeAnObj(c *cObjPtr) {
	cObjPtr->n += 11;
}

void main() {

c *cPtr;
cPtr = new c;

passPtr(cPtr);

c *cPtrArr[10];

cPtrArr[2] = new c;

passPtrArr(cPtrArr); // called with entire array

passPtr(cPtrArr[4]); // called with one element (also a pointer)

// fn. returnPtr() is given the entire array, sets the member var n 
// of the second item in the array (pointer to a c created with new)
// It returns only a pointer to that one element and the n val from 
// that one c is printed.

cout << "member n for 2nd element is: " << returnPtr(cPtrArr)->n << endl;

c *anotherC = new c;
anotherC->n = 14;
cout << "before entering fn. n is: " << anotherC->n << endl;
changeAnObj(anotherC);
cout << "and after returning, n is: " << anotherC->n << endl;

char k;
cin >> k; // to pause, if necessary

} // main()