c++ - 嵌套类中的静态成员是否具有封闭类的静态持续时间？

Question

如果我有嵌套类，并且这些嵌套类有静态成员，这些成员对于封闭类来说仍然是静态的吗？例如，如果我有

class Enclosing {
public:
    Enclosing();
private:
    class Nested {
    public:
        Nested();
    private:
        static int thing;
    };
};

如果我这样做

auto A = Enclosing();
auto B = Enclosing();

A 和 B 是否可以为 thing 设置不同的值？

Answer 1

Will A and B be able to have different values for thing?

不，它们不会有不同的值。所有实例都将看到相同的 thing 值；类的嵌套在这里没有影响。

static 成员变量“与类关联”(即与类实例关联的非静态成员)。 From cppreference ;

Static data members are not associated with any object. They exist even if no objects of the class have been defined. If the static member is declared thread_local (since C++11), there is one such object per thread. Otherwise, there is only one instance of the static data member in the entire program, with static storage duration.

Live sample .