Question

When I try to use a static_cast to cast a double* to an int*, I get the following error:

invalid static_cast from type ‘double*’ to type ‘int*’

Here is the code:

#include <iostream>
int main()
{
        double* p = new double(2);
        int* r;

        r=static_cast<int*>(p);

        std::cout << *r << std::endl;
}

I understand that there would be problems converting between a double and an int, but why is there a problem converting between a double* and an int*?

Answer 1

Aside from being pointers, double* and int* have nothing in common. You could say the same thing for Foo* and Bar* pointer types to any dissimilar structures.

static_cast means that a pointer of the source type can be used as a pointer of the destination type, which requires a subtype relationship.