如果理解了上节的constructor initializer list的行为,那么不难想到,相比于将正确的值在constructor body里赋给成员变量,不如直接在initializer list里给出。这是因为,constructor initializer list是直接初始化了数据成员(1步),而如果赋值在constructor body里,就是在进入body前进行了初始化,然后在body中进行赋值(2步)...
本文探讨构造函数初始值列表(constructor initializer list)这一C++特性，主要关注其行为、适用场景以及相关细节。构造函数初始值列表用于在构造函数定义时直接初始化数据成员，简化代码并提升效率。构造函数初始值列表的行为遵循三步初始化流程。首先，使用初始值列表中的值进行初始化（通过调用与实参相对应的构造...
myclass foo {10,20};//calls initializer_list constructormyclass bar (10,20);//calls first constructor 仅可以从braced-init-list推导出initializer_list<T>。这一过程中,编译器自动查询哪些构造函数可以用initializer_list<T>作为参数,并据此确定initializer_list的模板参数T的类型,从而对braced-init-list做类...
Furthermore,if a class doesn't have a default constructor, or you have aconstmember variable, youmustuse an initializer list: classA{public:A(intx){x_=x;}intx_;}classB{public:B():a(3),y(2)// 'a' and 'y' MUST be initialized in an initializer list;{// it is an error not ...
With C++ classes one can have the option of initializing the class's data members in the constructor's initializer list. Using constructor initializer lists in C++ Builder is discussed. It is shown that they represent the preferred way of initializing a class.Kent Reisdorph...
In the following example, our Foo(int, int) constructor has been updated to use a member initializer list to initialize m_x, and m_y: #include <iostream> class Foo { private: int m_x {}; int m_y {}; public: Foo(int x, int y) : m_x { x }, m_y { y } // here's ...
An object of type std::initializer_list is a lightweight proxy object that provides access to an array of objects of type const T. A std::initializer_list object is automatically constructed when: a braced-init-list is used to list-initialize an object, where the corresponding constructor acc...
“The instance member ‘widget’ can’t be accessed in an initializer” 错误是因为在初始化器列表中(constructor initializer list)访问了 widget 成员。这是因为在构造函数的初始化器列表中,对象的属性(包括 widget)还没有被初始化,因此不能在这里访问它们。
[translate] a(4)半自动焊接生产线; [translate] a保罗今天早上起床太晚了,没赶上校车 正在翻译,请等待... [translate] a我没有做对大家有帮助的文件 正在翻译,请等待... [translate] amember function or nested class in constructor initializer list 成员作用或被筑巢的类在建设者初程序名单 [translate] ...
Constructs an empty initializer list. Parameters (none) Complexity Constant Notes Despite a lack of constructors, it is possible to create non-empty initializer lists. Instances ofstd::initializer_listare implicitly constructed when: abraced-init-listis used inlist-initialization, including function-ca...