c++ Vector declared private in class but has a get function - c++

Question

If I have a class lets say like this in a separate .h file
class myclass{
private:
vector<string> data;
public:
vector <string>& getMydata(){
return this->data;
}
};
How do I then in separate .cpp access the data in the private vector?

Answer 1

the.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";
}
Output:
hello
world
Someone from the utside was here!

Answer 2

You separate the implementation into a .cpp the same way you do any function:
vector <string>& myClass::getMydata(){
return this->data;
}
The only difference it you'll need to show that you are implementing the one from the class by putting myClass:: in front of your implementation.
The compiler will allow a member function to access private data, even if it is defined outside the class definition.
i understand that. I guess what i mean to say is in main.cpp how would access the data?
Oh, I see. If you want to access it from main(), or some other non-member function, you need to call your getter:
int main() {
myclass foo;
foo.getMydata().push_back("We're modifying the vector from main()!");
}