Question

Will the destructor of the base class be called if an object throws an exception in the constructor?

Answer 1

If an exception is thrown during construction, all previously constructed sub-objects will be properly destroyed. The following program proves that the base is definitely destroyed:

struct Base
{
    ~Base()
    {
        std::cout << "destroying base\n";
    }
};

struct Derived : Base
{
    Derived()
    {
        std::cout << "throwing in derived constructor\n";
        throw "ooops...";
    }
};

int main()
{
    try
    {
        Derived x;
    }
    catch (...)
    {
        throw;
    }
}

output:

throwing in derived constructor
destroying base

(Note that the destructor of a native pointer does nothing, that’s why we prefer RAII over raw pointers.)