提升智能指针can be used with polymorphism,但是如何将子类强制转换回指针?
using namespace boost;
// ...
shared_ptr<SuperClass> a_ptr(new SubClass);
// ...
shared_ptr<SubClass> b_ptr = (shared_ptr<SubClass>)a_ptr; // Doesn't compile
最后一行不编译并给出error C2440: 'type cast' : cannot convert from 'boost::shared_ptr
<T>
' to 'boost::shared_ptr<T>
'
答案 0 :(得分:12)
您需要使用static_pointer_cast
:
struct B { virtual ~B() { } };
struct D : B { };
shared_ptr<B> bp(new D);
shared_ptr<D> dp(static_pointer_cast<D>(b));
(还有dynamic_pointer_cast
和const_pointer_cast
分别用于执行动态和const转换。)