从未知指针转换为类; 如何检查有效性？

class Base {
public:
    virtual ~Base() {}
};

class Derived : public Base {};

Base* pBase = new Derived;
Derived* pDerived = dynamic_cast<Derived*>(pBase);
if (pDerived) {
    // 转换成功，pDerived 是有效的
} else {
    // 转换失败，pBase 不是 Derived 的实例
}

std::shared_ptr<Base> pBase = std::make_shared<Derived>();
std::weak_ptr<Base> wpBase = pBase;
if (auto spDerived = std::dynamic_pointer_cast<Derived>(wpBase.lock())) {
    // 转换成功，spDerived 是有效的
} else {
    // 转换失败，wpBase 不是 Derived 的实例
}

std::unique_ptr<Base> pBase = std::make_unique<Derived>();
if (auto pDerived = dynamic_cast<Derived*>(pBase.get())) {
    // 转换成功，pDerived 是有效的
} else {
    // 转换失败，pBase 不是 Derived 的实例
}