How to pass a vector by copy, and by reference, to a function?

Question

    int main () {
       vector <int> vectorF;
       functionX <vector<int>&, long> (vectorF, 1L);
    }

    template <typename dataTypeA, 
              typename dataTypeB> dataTypeB functionX (dataTypeA argA, 
                                                       dataTypeB argB)
    {   
    }

This code changes the actual values in the vector, if modified in the function definition.

What is the way to pass the vector by copy?

Answer 1

Simply call the function as,

functionX (vectorF, 1L);  // ok! explicit function calling isn't needed

However, as a side not I would like to mention that making a copy of a whole vector just for a function doesn't make much sense. You can simply change the function definition to,

template <typename dataTypeA, typename dataTypeB>
dataTypeB functionX (const dataTypeA& argA, dataTypeB argB)
{                    ^^^^^^^^^^^^^^^^^ const reference 
}

if you are using this vector for reading purpose.

Answer 2

functionX <vector<int>, long> (vectorF, 1L);

Addind a & after the vector<int> will make the dataTypeA to be a reference to a vector. If you want a copy to a vector, remove the &