[Solved] Pre order traversal of a tree

[lainz]

Say I have two classes

Myobject
-name
-id
-quantity
-items: myclass

Myclass
- optionals: array of myobject
- additional: something else

A: myclass

A.optionals[0].items.optionals[0].name...

It starts on A that is myclass type. Containing an array of myobject type.

Then if items (myclass) is assigned or != Nil I must look for subitems, else stop and continue if remaining in another item or subitem

The order must be pre order traversal.

Any good examples you can point me?

PD: this is not homework. Thanks.

[rvk]

You can simply use a recursive function.
(sorry, no working examples, I'm on mobile)

Something like (pseudo code)

Code: [Select]

function foo(my: myclass)
begin
  for x being 0 to my.optionals.count - 1
  begin
     If my.optionals[x].items <> nil do
        foo(my.optionals[x].items)
     Handle my.optionals[x].rest
  end
  Handle my.additional
end
This should give you pre order traversal.

[julkas]

Alternative - use stack.

Code: Text  [Select][+][-]

1. push(root node)
2. while (stack not empty) {
3.   pop node
4.   proc node
5.   push node childs from the last to the first
6. }
7.  

[marcov]

Alternative - use stack.

Code: Text  [Select][+][-]

1. push(root node)
2. while (stack not empty) {
3.   pop node
4.   proc node
5.   push node childs from the last to the first
6. }
7.  

That code processes the root node before the children of the root node, and isn't systematically preorder. Fixed:

Code: Text  [Select][+][-]

1. push root node childs from the last to the first
2. push(root node)
3. while stack not empty do
4.    begin
5.       pop node
6.       proc node
7.       push node childs from the last to the first
8.    end
9.  

I assume the last to first bit is a matter of taste) or spec.

[julkas]

I use - https://en.wikipedia.org/wiki/Tree_traversal#Pre-order_(NLR)

[marcov]

Never mind, I was wrong.

[lainz]

Thanks rvk and others, it works pretty well with the recursive way.