1）代码

#include <iostream>
#include <vector>
#include <fstream>
class Point {
public:
    int x;
    std::string b;
    std::ofstream *of;
    int y;
};
int main() {
    std::vector<Point> points;
    std::ofstream outfile;
    outfile.open("tmp.txt"); 
    Point pt1 = {1,"b1", &outfile, 2};
    std::ofstream outfile2;
    Point pt2 = {3,"b2", &outfile2, 4};
    points.push_back(pt1);
    points.push_back(pt2); 
    std::cout<< points[0].x << ", " << points[0].b << ", "<< points[0].y << std::endl;
    std::cout<< points[1].x << ", " << points[1].b << ", "<< points[1].y << std::endl;
    *(points[0].of) << "hello world\n";
    points[0].of.close();    
    return 0;

2)报错

a2.vector.cpp: In function 'int main()':
a2.vector.cpp:23:18: error: request for member 'close' in 'points.std::vector<Point>::operator[](0).Point::of', which is of pointer type 'std::ofstream*' {aka 'std::basic_ofstream<char>*'} (maybe you meant to use '->' ?)
     points[0].of.close();
3）

(points[0].of).close();    

改成

(points[0].of)->close();    

4)输出结果

1, b1, 2
3, b2, 4
 

tmp.txt中也有数据

hello world
 

5）

最终代码是这样的

#include <iostream>
#include <vector>
#include <fstream>
class Point {
public:
    int x;
    std::string b;
    std::ofstream *of;
    int y;
};
int main() {
    std::vector<Point> points;
    std::ofstream outfile;
    outfile.open("tmp.txt"); 
    Point pt1 = {1,"b1", &outfile, 2};
    std::ofstream outfile2;
    Point pt2 = {3,"b2", &outfile2, 4};
    points.push_back(pt1);
    points.push_back(pt2); 
    std::cout<< points[0].x << ", " << points[0].b << ", "<< points[0].y << std::endl;
    std::cout<< points[1].x << ", " << points[1].b << ", "<< points[1].y << std::endl;
    *(points[0].of) << "hello world\n";
    (points[0].of)->close();    
    return 0;
}