Re: STL Vector - pass by reference?

Hi,

In an earlier thread entitled "STL vector - which style of for() loop?"
I had a function that could populate a vector (with a variable number of
strings) and pass it back to the caller, but people pointed out this
would create a "copy" of the vector and it may be better to pass by
reference. Doug Harrison offered this example:

----- example start -----

I would use pass-by-reference to avoid this needless cost, e.g.

vector<string>::size_type
void GetDeviceClasses(vector<string>& guids)
{
   guids.clear();
   // If you can estimate n, reserve can eliminate reallocations.
   // guids.reserve(n);
   ...
   returns guids.size();
}

----- example end -----

but when I came to actually code this, I ran into some problems. I
managed to code something that appears to achieve the objective, but my
code is almost "back-to-front" (in terms of * and &) of what Doug
posted. Can someone clarify?

----- my attempt -----

using namespace std; // just for this demo

vector<string> guids;
PopulateStrings(&guids);
cout << "Count of guids is now " << guids.size(); // prints 2

void PopulateStrings(vector<string> * guids)
{
   guids->clear();
   guids->push_back("test1");
   guids->push_back("test2");
}

----- end my attempt -----