1. 解释std::static_pointer_cast的基本概念 std::static_pointer_cast 是C++11 引入的一个模板函数,用于智能指针(如 std::shared_ptr 或std::weak_ptr)之间的类型转换。这种转换是编译时的强制转换,不会在运行时进行检查,类似于 static_cast,但专门用于智能指针,确保转换后的指针仍然保留智能指针的
// static_pointer_cast example #include <iostream> #include <memory> struct A { static const char* static_type; const char* dynamic_type; A() { std::cout << "construct A " << std::endl; dynamic_type = static_type; } }; struct B: A { static const char* static_type; B() {...
std::shared_ptr<T> static_pointer_cast( const std::shared_ptr<U>& r ) noexcept; (1) (C++11 起) template< class T, class U >std::shared_ptr<T> static_pointer_cast( std::shared_ptr<U>&& r ) noexcept; (2) (C++20 起) template< class T, class U >std::shared_ptr<T> ...
std::pair包含两个元素，std::tuple 可以同时包含多个元素，它拥有 struct 的表现，但是无需定义实际的...
问如何避免在使用派生实例调用模板基类的友元函数时必须使用“std：：static_pointer_castEN《C++面向对象...
r-the pointer to convert Notes The expressionsstd::shared_ptr<T>(static_cast<T*>(r.get())),std::shared_ptr<T>(dynamic_cast<T*>(r.get()))andstd::shared_ptr<T>(const_cast<T*>(r.get()))might seem to have the same effect, but they all will likely result in undefined behavior...
std::shared_ptr<T> static_pointer_cast( const std::shared_ptr<U>& r ) noexcept; (1) (since C++11) template< class T, class U > std::shared_ptr<T> static_pointer_cast( std::shared_ptr<U>&& r ) noexcept; (2) (since C++20) template< class T, class U > std::shared_ptr...
self是一个std::weak_ptr<Widget>,它不会增加引用计数。std::weak_ptr用于记录Widget对象,但不会影响对象的生命周期。std::static_pointer_cast用于将self转换为std::shared_ptr<Widget>,以便将其存储在processedWidgets中。 (2)通过std::shared_ptr引用对象 ...
static_pointer_cast、 dynamic_pointer_cast、 const_pointer_cast #include <iostream> #include <memory> using namespace std; int main() { shared_ptr<void> spv(new int(1)); shared_ptr<int> spe(static_cast<int*>(spv.get())); shared_ptr<int> spn = static_pointer_cast<int>(spv); cou...
shared_ptr的类型转换不能使用一般的static_cast,这种方式进行的转换会导致转换后的指针无法再被shared_ptr对象正确的管理。应该使用专门用于shared_ptr类型转换的 static_pointer_cast<T>() , const_pointer_cast<T>() 和dynamic_pointer_cast<T>()。