问题标出了， A(); //不应该A::A()吗？

#include <iostream>
#include <string>
using namespace std;

class A
{
public:
    A()
    {
        cout << "A constructor" << endl;
    }

    ~A()
    {
        cout << "A destructor" << endl;
    }
};

int main()
{
    A();  //不应该A::A()吗？

    cout<<"end xxx\n";
    cout<<"end yyy\n";

}