Visual Studio C6385 warning c++

Question

I got the following warning because of the variable a :

C6385: Reading invalid data from 'z': the readable size is 'a*4' bytes, but '12' bytes may be read

In addition, the return line is marked green in my IDE. How should I fix this?

int function(int a)
{
    int* z = new int[a];
    return z[2];
}

I'm using Microsoft Visual Studio 16.6.2.

Answer 1

I don't know why you use dynamic memory allocation. My recommendation to avoid all the commented problems is to use a vector

int function(int a)
{
    std::vector<int> z(std::max(3, a));
    return z[2];
}

It will initialize the elements, clean up memory and guarantee the size. An alternative is to throw if the element doesn't exist

int function(int a)
{
    std::vector<int> z(a);
    return z.at(2);
}

or

int function(int a)
{
    if (a < 3) throw;
    std::vector<int> z(a);
    return z[2];
}

Answer 2

I figured out: adding if (a < 3) a = 3; will actually do the job. No warning anymore. Thanks for help anyway.