关于类中的const 及 static成员初始化实例

class A2
{
private:
    static const int m_all = 3;
    const int m_const;
    static int m_static;
public:
    A2(int i_const = 12):m_const(i_const)
    {
    
    }
};

int A2::m_static = 4;