Question

I’ve heard that you should usually “delete” whenever you use “new”, yet when I run a simple test program (below), it doesn’t seem to make a difference which numbers I put for arraySize or numLoops. Does this cause a memory leak?

#include <iostream>

int main()
{
    double *array;
    const int arraySize = 100000;
    const int numLoops = 100000;

    for (int i = 0; i < numLoops; i++)
    {
        // do I need to call "delete [] array;" here?
        array = new double[arraySize];
    }

    int x;
    std::cin >> x; // pause the program to view memory consumption

    delete [] array;

    return 0;
}

Answer 1

No, it’s not sufficient.

Each time you call new or new[], some memory is allocated, and you are given the address of that memory (in order to be able to use it). Each piece of memory must eventually be deleted (or delete[]d).

You are storing that address in array, but then immediately overwriting it on the next iteration. Therefore you have no way of delete-ing all of pieces of memory that you’ve been allocated. Therefore you have a memory leak.