Cannot cast from 'TFmxChildrenList' to 'TRectangle *'

I'm new to using C++ Builder so apologies if I'm making any rudimentary mistakes.

I have drawn out a TLayout named 'Collection' with a 5x5 grid of TRectangles within it. The cells are named like so "CellXY". I presumed it might be easier to draw these out on the Form rather than instantiating them with code, now I'm thinking otherwise, but I would still like to solve the problem this way to better my understanding.

I'm trying to write a method which will return a pointer to a TRectangle whose name contains the coordinates passed to the method.

Currently, I'm trying to do this by iterating through the children of the TLayout Collection:

TRectangle* __fastcall TForm2::getCellRectangleFromCoordinate(int X, int Y){
    TRectangle* targetCell = NULL;
    char targetCellName[6];
    sprintf(targetCellName, "Cell%i%i", X, Y);
    for (int cIndex = 0; cIndex < Collection->ChildrenCount; ++cIndex)
    {
        TRectangle* cellRect = (TRectangle*) Collection->Children[cIndex]; // Error Here
        string cellName = cellRect->Name;
        if (targetCellName == cellName) {
            targetCell = cellRect;
            break;
        }
    }
    return targetCell;
}

But I am given an error reading:

E2031 Cannot cast from 'TFmxChildrenList' to 'TRectangle *'

If anyone could help, I'd be very grateful!

The Children property is a pointer to a class type (TFmxChildrenList) that internally holds an array of objects. Children is not the actual array itself, like you are trying to treat it as.

Children[cIndex] is using pointer arithmetic, which is not what you want in this situation. You need to use the Children->Items[] sub-property instead, by changing this statement:

Collection->Children[cIndex]

To either this:

Collection->Children->Items[cIndex]

Or this:

(*(Collection->Children))[cIndex]