/*
 * -----------------------------------------------------
 * CS2S03/SE2S03, September 2011
 * Assignment 2, Question 1
 * File: PE0211.cpp
 * -----------------------------------------------------
 *
 * The program tests the function IndexArray(n) that returns a 
 * pointer to a dynamically allocated integer array with n 
 * elements, each of which is initialized to its own index.
 * 
 * -----------------------------------------------------
 */

#include "genlib.h"
#include "simpio.h"
#include <iostream>

/* Private function prototypes */

int* IndexArray(int n);

/* Main program */

int main() {
    int *ip;
    int n;

    cout << "Enter a positive integer: ";
    n = GetInteger();

    ip = IndexArray(n);

    if (ip != NULL) {
        cout << "The elements in the array:" << endl;
        for (int i = 0; i < n; i++) {
            cout <<  "  " << ip[i];
        }
    } else {
    cout << "An empty array.";
    }
	
    cout << endl;

    return 0;	
}

/*
 * Function: IndexArray
 * Usage: ip = IndexArray(n);
 * -----------------------------------------------------
 * This function returns a pointer to a dynamically
 * allocated integer array with n elements, each of which 
 * is initialized to its own index.
 * It returns a null pointer if n is not positive.
 */

int* IndexArray(int n) {
    if (n <= 0) return NULL;

    /* Dynamic integer array declaration */
    int* myArray = new int[n];
    if (myArray == NULL) Error("Fail to allocate memory.");

    /* initialize the array */
    for (int i = 0; i < n; i++) {
        myArray[i] = i;
    }

    return myArray;
}