Super Noob C++ variable help

Ok, I must preface this by stating that I know so so little about c++ and am hoping someone can just help me out...

I have the below code:

string GoogleMapControl::CreatePolyLine(RideItem *ride)
{
    std::vector<RideFilePoint> intervalPoints;
    ostringstream oss;

    int cp;
    int intervalTime = 30;  // 30 seconds
    int zone =ride->zoneRange();
    if(zone >= 0)
    {
        cp = 300;  // default cp to 300 watts
    }
    else
    {
        cp = ride->zones->getCP(zone);
    }

    foreach(RideFilePoint* rfp, ride->ride()->dataPoints())
    {
        intervalPoints.push_back(*rfp);
        if((intervalPoints.back().secs - intervalPoints.front().secs) > intervalTime)
        {
            // find the avg power and color code it and create a polyline...
            AvgPower avgPower = for_each(intervalPoints.begin(),
                                         intervalPoints.end(),
                                         AvgPower());
            // find the color
            QColor color = GetColor(cp,avgPower);
            // create the polyline
            CreateSubPolyLine(intervalPoints,oss,color);
            intervalPoints.clear();
            intervalPoints.push_back(*rfp);
        }

    }
    return oss.str();
}


void GoogleMapControl::CreateSubPolyLine(const std::vector<RideFilePoint> &points,
                                         std::ostringstream &oss,
                                         QColor color)
{
    oss.precision(6);
    QString colorstr = color.name();
    oss.setf(ios::fixed,ios::floatfield);
    oss << "var  polyline  = new GPolyline([";

    BOOST_FOREACH(RideFilePoint rfp, points)
    {
        if (ceil(rfp.lat) != 180 && ceil(rfp.lon) != 180)
        {
            oss << "new GLatLng(" << rfp.lat << "," << rfp.lon << ")," << endl;
        }
    }

    oss << "],\"" << colorstr.toStdString() << "\",4);";

    oss << "GEvent.addListener(polyline, 'mouseover', function() {" << endl
    << "var tooltip_text = 'Avg watts:" << avgPower <<" <br> Avg Speed: <br> Color: "<< colorstr.toStdString() <<"';" << endl
    << "var ss={'weight':8};" << endl
    << "this.setStrokeStyle开发者_运维问答(ss);" << endl       
    << "this.overlay = new MapTooltip(this,tooltip_text);" << endl
    << "map.addOverlay(this.overlay);" << endl
        << "});" << endl
    << "GEvent.addListener(polyline, 'mouseout', function() {" << endl
    << "map.removeOverlay(this.overlay);" << endl
    << "var ss={'weight':5};" << endl
    << "this.setStrokeStyle(ss);" << endl
    << "});" << endl;

    oss << "map.addOverlay (polyline);" << endl;
}

And I'm trying to get the avgPower from this part:

AvgPower avgPower = for_each(intervalPoints.begin(),
                                             intervalPoints.end(),
                                             AvgPower());

the first part to cary over to the second part:

<< "var tooltip_text = 'Avg watts:" << avgPower <<" <br> Avg Speed: <br> Color: "<< colorstr.toStdString() <<"';" << endl

But of course I haven't the slightest clue how to do it... anyone feeling generous today?

Thanks in advance

Well you didn't state the problem with the code other than it doesn't work. I'm suspicious of your use of AvgPower() in the for_each. Also, you have AvgPower as a class. why not a double or something? For this code I would have expected to see something like this:

PowerType addIntervals(const RideFilePoint &p1, const RideFilePoint &p2) {
    //Add and return.
}
   ...
   ...
PowerType total = accumulate(i.begin(), i.end(), PowerType(0.0), &addIntervals);
avg = total/i.length();

read these docs carefully: http://www.sgi.com/tech/stl/accumulate.html

It seems like you are asking how to access the local variable avgPower within a different function (sorry if I am misunderstanding). This is less about c++ specifically and more about functional or object oriented design. There are many different ways to do this, but here are the sane ones I can think of, in the order of my preference.

1. Create avgPower (and color), within CreateSubPolyLine. There doesn't really seem to be any reason they are in CreatePolyLine anyway. Implement a separate call if there are other consumers. The function signature would change to

   void GoogleMapControl::CreateSubPolyLine(const std::vector &points, std::ostringstream &oss)

2. Include it in the function's paramemters, e.g., change the signature to:

   void GoogleMapControl::CreateSubPolyLine(const std::vector &points, std::ostringstream &oss, const QColor& color, const AvgPower& avgPower)

3. Put it in a member variable of GoogleMapControl. It doesn't seem like this would be a bad design choice in my opinion.