C++ Dynamic Memory Allocation

#include <iostream>
using namespace std;

int* createList(int size){
    if (size <= 0) return nullptr;
    else {
        int* list = new int[size];
        for (int i = 0; i < size; ++i)
             list[i] = rand() % 1000;
        return list;
    }
}

void display (int* a, int size){
    for (int i =0; i < size; ++i)
        cout << a[i] << "  " ;
}

int main()
{
    srand(time(0));
    int* list1 = createList(10);
    display(list1,10);
    cout << endl << endl;
    int* list2 = createList(15);
    display(list2,15);
    delete [] list1;
    delete [] list2;
}