Question

I am now starting Dynamic Memory Allocation in class and have a ok understanding of it but can’t completely use it properly. I feel like I may not be so great with pointers either :p

My instructor gave instructions to create a function named readArray that will prompt the user for a number to use as a size to dynamically create a integer array of that size. I am then to assign the new array to a pointer. I then am supposed to prompt the user to fill the array. I then am supposed to return both the newly created array and the size.

I can not figure out how to return the array though, and I thought when dynamically allocating memory you were supposed to delete the allocation after using it to prevent leaks.

The array and size must be returned to main so I can pass it to other functions such as a sorting function.

I would greatly appreciate any help I can get as my thought process with this keeps going in the wrong direction.

#include <iostream>
using namespace std;

int* readArray(int&);
void sortArray(int *, const int * );

int main ()
{
   int size = 0;
   int *arrPTR = readArray(size);
   const int *sizePTR = &size;
   sortArray(arrPTR, sizePTR);

   cout<<arrPTR[1]<<arrPTR[2]<<arrPTR[3]<<arrPTR[4];

        system("pause");
        return 0;
}


int* readArray(int &size)
{
   cout<<"Enter a number for size of array.\n";
   cin>>size;
   arrPTR = new int[size];

   for(int count = 0; count < (size-1); count++)
   {    
       cout<<"Enter positive numbers to completely fill the array.\n";
       cin>>*(arrPTR+count);
   }

   return arrPTR;
}

Answer 1

To return an array: declare readArray() as int* readArray() [return an int* instead of an int], and return arrPTR instead of size. This way, you return the dynamically allocated array which arrPTR points to.

Regarding the delete: When you are done using the array, you should indeed delete it. In your example, do it before return 0 in your main() function.

Make sure that since you allocated memory with new[], you should also free it with delete[], otherwise – your program will have a memory leak.