`std::vector` 'substring concatenator'

The point of this is to concatenate a vector of std::strings into one string starting at an index of the vector.

std::string vectorSubstr(std::vector vec, int startPos, char seperator)
{
    std::stringstream ss;

    for (int i = startPos; i < vec.size(); i++)
    {
        if (i == startPos)
        {
            ss << vec[i];
        }
        else
        {
            ss << seperator << vec[i];
        }
    }

    return ss.str();
}

Is there anything wrong with this approach? Should I be using a stringstream or just concatenating strings?

If you are just trying to concatenate vector elements, why not use the following approach:

std::string seperator = " ";
std::string vectorElementHolder;

for (const auto& word : vec){

    vectorElementHolder += word + seperator;

}

Simple and effective, assuming you use C++11.
If you want to change the index where you start, you could always declare an iterator as such vector::iterator to point to the index and go from there.

StackExchange Code Review Q#92111, answer score: 2