CODEWITHSUNDEEP
c++c++11vector
LoadRunner
LoadRunner

Reputation: 43

C++11 Implementing a Move Contructor and Moving a Member Vector

Ok, I will put up the code first, and then ask my question.

#include<vector>
#include<string>

using std::vector;
using std::string;

class MyStringContainer
{
public:
   MyStringContainer(vector<string> strVec): _strVec(strVec){;}
   MyStringContainer(MyStringContainer&& rhs): _strVec(move(rhs._strVec)){;}
private:
   vector<string> _strVec;
}

int main()
{
  vector<string> dummyVec(1000000, "arbitrary string");

  MyStringContainer strCon1(dummyVec);
  MyStringContainer strCon2(move(strCon1));
}

So I just spent some time learning move semantics, and I think I got the basic idea of it concerning how to swap raw and/or smart pointers around and setting the discarded pointers to nullptr. However when dealing with vectors (and all the containers that implement move semantics), I am not 100% sure if my code above will properly "nullptr" the pointer elements of the source vector. Does the implementation of the std::vector class already handle this for me?

Upvotes: 1

Views: 141

Answers (2)

Chris Drew
Chris Drew

Reputation: 15334

The std::vector class will handle this for you. In fact in this case you could use the implicitly generated move constructor. Also if your constructor takes the vector<string> by value, which is fine, you may want to use std::move to move it into the member variable to save a copy:

#include<vector>
#include<string>

class MyStringContainer {
private:
   std::vector<std::string> strVec_;
public:
   MyStringContainer(std::vector<std::string> strVec): strVec_(std::move(strVec)){ }
};

int main()
{
  std::vector<std::string> dummyVec(1000000, "arbitrary string");
  MyStringContainer strCon1(std::move(dummyVec));
  MyStringContainer strCon2(std::move(strCon1));
}

Note I have used std::move to move the dummyVec into the constructor as well to save another copy.

Upvotes: 1

Blaz Bratanic
Blaz Bratanic

Reputation: 2279

Implementation of the std::vector handles this for you.

Upvotes: 2

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