Question

Am i doing this right, I want a map with a Integer as key, and struct as value. What is the easiest way to, say I want the object at 1. How do I retrieve the value of isIncluded? The last two lines in the code, I tried doing it, but then I realized I don´t really know what is the way to retrieving values of structs in a numbered Map array.

Do I need to call cells.get(1) and assign that to a new temporarely struct to get its values?

/** set ups cells map. with initial state of all cells and their info*/
void setExcludedCells (int dimension)
{
    // Sets initial state for cells
    cellInfo getCellInfo;
    getCellInfo.isIncluded = false;
    getCellInfo.north = 0;
    getCellInfo.south = 0;
    getCellInfo.west = 0;
    getCellInfo.east = 0;

    for (int i = 1; i <= (pow(dimension, 2)); i++)
    {
        cells.put(i, getCellInfo);
    }
    cout << "Cells map initialized. Set [" << + cells.size() << "] cells to excluded: " << endl;
    cells.get(getCellInfo.isIncluded);
    cells.get(1);
}

the Map, is declared as an private instance variable like this:

struct cellInfo {
    bool isIncluded;
    int north;  // If value is 0, that direction is not applicable (border of grid).
    int south;
    int west;
    int east;
};
Map<int, cellInfo> cells;       // Keeps track over included /excluded cells

Answer 1

From the documentation for Map, it appears that .get() returns a ValueType.

You would use it thus:

// Display item #1
std::cout << cells.get(1).isIncluded << "\n";
std::cout << cells.get(1).north << "\n";

Or, since the lookup is relatively expensive, you could copy it to a local variable:

// Display item #1 via initialized local variable
cellInfo ci = cells.get(1);
std::cout << ci.isIncluded << " " << ci.north << "\n";

// Display item #2 via assigned-to local variable
ci = cells.get(2);
std::cout << ci.isIncluded << " " << ci.north << "\n";

---

My best advice is to use the standard library’s std::map data structure instead:

// Expensive way with multiple lookups:
std::cout << cells[1].isIncluded << " " << cells[1].north << "\n";

// Cheap way with one lookup and no copies
const cellinfo& ci(maps[1]);
std::cout << ci.isIncluded << " " << ci.north << "\n";