Initial Value of Dynamically-Allocated Memory in C++

Question

In C++, when you dynamically allocate an array of int, are the values of the ints undefined or initialized to 0?

    int *array = new int[50];

Answer 1

The term is uninitialized. But it depends how you initialize the array. You could value-initialize it:

int *array = new int[50]();

and the values would be 0.

If you leave it uninitialized, you can't know what values are there because reading from them would be undefined behavior.

Answer 2

If you use vectors instead of arrays, you will get an initial value of 0 for all elements:

std::vector<int> v(50);

If you want a different default value, you can specify one:

std::vector<int> v(50, 42);

An additional benefit of vectors is that you don't have to manually release the underlying array.