C ++初始化构造函数中的未命名结构成员

Question

example:

class A 
{
public:
    A();
private:
    struct {int x, y; } position_;
};

my question is: how to init position_.x and position_.y before the constructor function body? like:

A::A()     //init position_.x and position_.y here
{
}

Answer 1

Just use a normal constructor initializer list:

A::A()
    : position_{0, 0}
{
}

Answer 2

You can initialize it like any data member ¹ : in the constructor initialization list:

A() : position_{1,2} {}    

at the point of declaration:

struct {int x, y;} position_{1, 2};

or both.

---

^{1 Assuming you have C++11 or higher}