c++ Vector在类中声明为私有(private)但具有get函数

Question

如果我有一个类，让我们在单独的 .h 文件中这样说

class myclass{
  private:
     vector<string> data;
  public:
     vector <string>& getMydata(){
       return this->data;
     }
};

然后如何在单独的 .cpp 中访问私有(private) vector 中的数据？

Answer 1

.hpp

#include <string>
#include <vector>

class myclass{
private:
     std::vector<std::string> data;

public:
     // put some data in it when it's default constructed
     myclass() : data{"hello", "world"} {}

     std::vector<std::string>& getMydata() {
         return data;
     }
};

main.cpp

#include "the.hpp"
#include <iostream>

int main()
{
    myclass instance;

    // get reference to the data in the instance
    std::vector<std::string>& data_ref = instance.getMydata();

    // use the data. data_ref is a reference to exactly the same vector as in "instance"
    data_ref.push_back("Someone from the utside was here!");

    // check result
    std::cout << instance.getMydata()[0] << "\n";
    std::cout << instance.getMydata()[1] << "\n";
    std::cout << instance.getMydata()[2] << "\n";   
}

输出:

hello
world
Someone from the utside was here!