Returning an empty vector of strings if key is not found

Question

I know it is a very bad idea, so other suggestions on how to do it efficiently will be well-received.

Here\'s the thing. I have map

Answer 1

Most of the time you don't need a copy of the vector to be returned, a const reference will do just as well. You can always make a copy later if you need to.

Also you don't need to iterate through a map, they're optimized for searching with the find method.

const vector & returnEdges(string key)
{
    map >::iterator it = outgoing.find(key);
    if (it == outgoing.end())
    {
        static vector empty_vector;
        return empty_vector;
    }
    return it->second;
}