Thread: Returning reference of vector

  1. #1
    SAMARAS std10093's Avatar
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    Returning reference of vector

    Example code:
    Code:
    #include <iostream>
    #include <vector>
    using namespace std;
    
    class A{
    private:
        vector<int> v;
    public:
        A() { for(size_t i = 0 ; i < 4 ; ++i) v.push_back(i); }
        vector<int>& getV() {return v;}
    };
    
    int main()
    {
        A a;
        vector<int> foo = a.getV();
        
        return 0;
    }
    I read somewhere, that we can imagine the reference as a pointer to the vector.
    So, my question is:
    Let's assume that instance of class A, named a, was created with new. We call a.getV() to foo and then we call the destructor of a.
    foo is safe? Is the copy constructor of std::vector called?
    Code - functions and small libraries I use


    It’s 2014 and I still use printf() for debugging.


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  2. #2
    Registered User
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    3,445
    your main() function is making a copy of the vector inside the class, so in this case it would be perfectly safe. if you're storing a reference:

    Code:
    vector<int>& foo = a.getV();
    then you need to remember that it becomes invalid the instant you delete the object.
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