C #: not all code paths return a value

Question

I am writing a simple WinForms application in which I allow the user to drag and drop TreeNodes in a TreeView control. One of the rules that I apply is that the user is not allowed to drag the TreeNode into one of his own children. I wrote the following function in a recursive style to check the parenthood of the node destination. After compilation, I get an error that not all code paths return a value for this function. As far as I can tell, I have a statement about returning to all possible branches of this logic ... but I'm obviously mistaken. Can someone please indicate my mistake, please.

    private bool IsDestinationNodeAChildOfDraggingNode(TreeNode draggingNode, TreeNode destinationNode) {
        if (draggingNode.Nodes.Count == 0) 
            return false;
        else {
            if (draggingNode.Nodes.Contains(destinationNode)) 
                return true;
            else {
                foreach (TreeNode node in draggingNode.Nodes) 
                    return IsDestinationNodeAChildOfDraggingNode(node, destinationNode);
            }
        }
    }

Answer 1

, , . foreach, ? , .

, , :

private bool IsDestinationNodeAChildOfDraggingNode(TreeNode draggingNode, TreeNode destinationNode) {
  // special case, no children
  if (draggingNode.Nodes.Count == 0) 
    return false;

  // check if the target is one of my children
  if (draggingNode.Nodes.Contains(destinationNode)) 
     return true;

  // recursively check each of my children to see if one of their descendants is the target
  foreach (TreeNode node in draggingNode.Nodes) 
    if (IsDestinationNodeAChildOfDraggingNode(node, destinationNode)) 
        return true;

  // didn't find anything
  return false;
}

, - , :

private bool IsDestinationNodeAChildOfDraggingNode(TreeNode draggingNode, TreeNode destinationNode) {
  bool retVal = false;

  if (draggingNode.Nodes.Count != 0) {

    // check if the target is one of my children
    if (draggingNode.Nodes.Contains(destinationNode)) {
      retVal = true;
    } else {

      // recursively check each of my children to see if one of their descendants is the target
      foreach (TreeNode node in draggingNode.Nodes) 
        if (IsDestinationNodeAChildOfDraggingNode(node, destinationNode)) {
          retVal = true;
          break;
        }
    }
  }

  return retVal;
}

Answer 2

, , draggingNode.Nodes , else , .

, :

foreach (TreeNode node in draggingNode.Nodes) 
     return IsDestinationNodeAChildOfDraggingNode(node, destinationNode);

return false

Answer 3

, return foreach, , draggingNode.Nodes , .

private bool IsDestinationNodeAChildOfDraggingNode(TreeNode draggingNode, TreeNode destinationNode) {
    if (draggingNode.Nodes.Count == 0) 
        return false;
    else {
        if (draggingNode.Nodes.Contains(destinationNode)) 
            return true;
        else {
            foreach (TreeNode node in draggingNode.Nodes) 
            {
                return IsDestinationNodeAChildOfDraggingNode(node, destinationNode);
            }
            return false; // <-- here for example
        }
    }
}

, , return. , Jherico, .

Answer 4

, draggingNodes.Nodes ? .

Answer 5

, foreach , foreach . if/else/foreach .

Answer 6

, # , foreach , .

Answer 7

Else -.

:

private bool IsDestinationNodeAChildOfDraggingNode(TreeNode draggingNode, TreeNode destinationNode) {
if (draggingNode.Nodes.Count == 0) 
        return false;
else {
       if (draggingNode.Nodes.Contains(destinationNode)) 
            return true;
       else {
            foreach (TreeNode node in draggingNode.Nodes) 
            return IsDestinationNodeAChildOfDraggingNode(node, destinationNode);
            }
    }
//Return something here.
}