_cast<A*>(this), this){}};structBase{virtual~Base(){}};structDerived:Base{virtualvoidname(){}};intmain(){D d;// 最终派生对象A&a=d;// 向上转换,可以用 dynamic_cast,但不是必须的[[maybe_unused]]D&new_d=dynamic_cast<D&>(a);// 向下转换[[maybe_unused]]B&new_b=dynamic_cast<...
dynamic_cast在继承层级中转换 const_cast添加或移除cv限定符 reinterpret_cast转换类型到无关类型 C 风格转换以static_cast、const_cast及reinterpret_cast的混合转换一个类型到另一类型 new创建有动态存储期的对象 delete销毁先前由 new 表达式创建的对象,并释放其所拥有的内存区域 ...
dynamic_cast and polymorphic typeid in constant expressions P1327R1 10 9 19.28 (16.9)* 11.0.3* 5.1 2021.1 20.7 12.0 11.0 Changing the active member of a union inside constexpr (FTM)* P1330R0 9 9 19.10* 11.0.3* 5.1 2021.1 20.7 12.0 11.0 Coroutines (FTM)* (FTM)* P0912R5LWG3393 ...
dynamic_caststructBase{virtual~Base(){}};structDerived:Base{voiddf(){std::cout<<"df()\n";}};Base*bp1=new Base;Base*bp2=new Derived;if(Derived*p=dynamic_cast<Derived*>(bp1))// cast fails, returns nullptrp->df();// not executedif(autop=dynamic_cast<Derived*>(bp2))// cast ...
if( x < 0 ) break; cout << x << endl; x++; } break语句只能跳出本层循环,假如你要跳出一个三重嵌套的循环,你就要使用包含其它的逻辑或者用一个goto语句跳出这个嵌套循环. case 在switch里面用来检测匹配 . default,switch catch catch 语句通常通过throw语句捕获一个异常. ...
2) 纯右值表达式不能是多态的[polymorphic]:纯右值表达式标识对象的动态型别总是表达式的型别。[the dynamic type of the object it identifies is always the type of the expression. ] 3) 非类[non-class]的纯右值不能被const或volatile关键字标识[cv-qualified]。
std::bad_cast This can be thrown by dynamic_cast. std::bad_exception This is useful device to handle unexpected exceptions in a C++ program. std::bad_typeid This can be thrown by typeid. std::logic_error An exception that theoretically can be detected by reading the code. std::domain_...
A prvalue cannot be polymorphic: the dynamic type of the object it identifies is always the type of the expression. (纯右值不能是动态类型) A non-class non-array prvalue cannot be cv-qualified. (不是class也不是数组的纯右值不能声明为const, volatile, const-volatile) ...
const_cast, static_cast, dynamic_cast, reinterpret_cast und typeid sind nicht enthalten, da sie immer eindeutig sind. Einige der Operatoren haben alternative Schreibweisen (z.B. and für &&, or für ||, not für !, usw.). Siehe auch Auswertungsreihenfolge von Operator-Argumenten zur...
dynamic_cast else enum explicit export extern false float for friend goto if inline int long mutable namespace new noexcept not not_eq nullptr operator or or_eq private protected public reflexpr register reinterpret_cast requires return short signed sizeof static static_assert static_cast struct swi...