I'm confused about data structs and classes

[JJJSSS]

In my class, we went over this stuff briefly and now that it's time to apply it, I'm completely confused. The book hasn't helped much either.

MassData getMassData(T x[], T y[], T m[], int numDataPoints);

MassData getMassData(T x[], T y[], T m[], int numDataPoints){
  
  MassData massData;
  massData.cenMassX = 0;
  massData.cenMassY = 0;
  massData.totMass  = 0;
  
  return massData;
}

Here's the portion of my code that is relevant. Not only am I confused about finding the center of mass of the 13-sided irregular shape (given its coordinates and side lengths), but how I would output this is my main function.

How would I output something like:
Total Mass:
Center of Mass:

Obviously those statements use cout, but I don't know how to output the calculated values.

[3TXyhbRD]

You want to output the members of a struct? Is that your question? If yes you could do it this way (C):

#include <cstdio>

int main()
{
    MassData massData;
    // initialization and calculus...
    printf("%d %d\n", massData.cenMassX, massData.cenMassY); // assuming those two members are int
    return 0;
}

Or the C++ way:

#include <iostream>

using namespace std;

int main()
{
    MassData massData;
    // initialization and calculus...
    cout<<massData.cenMassX<<" "<<massData.cenMassY<<endl;
    return 0;
}

[JJJSSS]

Thanks. Now I have to figure out how to calculate the center of mass coordinates.

[JJJSSS]

Does this look correct for finding the total mass?
Here's my output code:
cout << "Total Mass: " << massData.totMass << endl;

  int mass = 0;
  
  MassData massData;
  massData.cenMassX = 0;
  massData.cenMassY = 0;
  
  for(int i = 0; i <= numDataPoints; ++i){
    mass = m[i];
    massData.totMass += mass;
  }
  
  return massData;
}

[3TXyhbRD]

Yep, looks good.