_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<...
4) 如果e 是对多态类型引用的 dynamic_cast,那么该集合由 std::bad_cast 组成。5) 如果e 是应用到多解引用指向多态类型指针的 typeid,那么该集合由 std::bad_typeid 组成。6) 如果e 是一个拥有非常量数组大小的 new 表达式,且选择的分配函数拥有非空的潜在异常集合,那么该集合由 std::bad_array_new_...
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 ...
5.2.10 Reinterpret cast [expr.reinterpret.cast] See also const_castconversionadds or removes const static_castconversionperforms basic conversions dynamic_castconversionperforms checked polymorphic conversions explicit castspermissive conversions between types ...
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. ...
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) ...
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]。
intx =static_cast<int>(President::MCKINLEY);//can specify any integer data type as the underlying typeenumclassDay:char{MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY}; 6. Templates template<classT>voidswap(T &i, T &j) { T temp = i; i = j; j = temp; }swap(a, b);...
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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...