Question

I have encountered the following code:

    class a {
    public:

        void *  operator new(size_t l, int nb);
        double  values;
    };
void *a::operator new (size_t l,int n)
{
    return new char[l+ (n>1 ? n - 1 : 0)*sizeof(double)];
}

From what I get it is then used to have an array like structure that start at “values”:

double* Val = &(p->a->values) + fColumnNumber;

My question is :
is there a memory leak? I am very new to overloading new operator, but I’m pretty sure that the memory allocated is not deallocated properly. Also does that mean I can never create a “a” class on the stack?

thanks

Answer 1

I believe it technically produces UB as it is, though it’s a form of UB that will probably never cause a visible side effect (it’s using new [], but I believe that’ll get matched up with delete — but for char, this usually won’t cause a visible problem).

IMO, it’s almost worse that it’s using a new expression to allocate what should really be raw bytes instead of objects. If I were doing it, I’d write it like:

void *a::operator new (size_t l,int n)
{
    return ::operator new(l+ (n>1 ? n - 1 : 0)*sizeof(double));
}

You’d match that up with:

void a::operator delete(void *block)
{
    ::operator delete(block);
}