使用g++编译一个简单的cc文件

#include <iostream>
using namespace std;
class Base{
private:
int lock_;
int data_;
public:
void read_from(std::istream &i){

}
void write_to(int i){

}
virtual ~Base(){

}
private:
virtual void read_from_impl(std::istream &)=0;
virtual void write_to_impl(std::ostream &) const =0;
};
class XMLReaderWriter:public Base{
private:
virtual void read_from_impl(std::istream &){

}
virtual void write_to_impl(std::ostream &) const{

}
public:
void display(){
cout<<"display /n"<<endl;
}
};
int main()
{
XMLReaderWriter *xml=new XMLReaderWriter();
xml->display();
}