const放在只读不写权限的静态成员函数前，VS2019语法不报错。可以正常运行。
class Airplane
{
public:
static int ApNum;
public:
Airplane() { ApNum++; }
const static int GetApNum(){ return ApNum; }
};
int Airplane::ApNum = 0;
int main(void)
{
Airplane *Apoint = new Airplane[2]{Airplane(),Airplane()};
cout<<Apoint->GetApNum()<<endl;
}
