CODEWITHSUNDEEP
schemepseudocoderacket
Achilles
Achilles

Reputation: 741

Accessing a variable field within a node

Hi I am new to Racket using it for a binary tree structure.

Using the following structure 

(define-struct human(age hight))

I have created the following object/variable/human 

(define James(make-human 10 50))

If I have a node in a binary tree structure

(define-struct node (left human right))

How can I compare a different object's hight (say Michael) with James given that James is within the node, so for an example:

 (define (insert-human-into-tree human node)
  (cond
    [(empty? node)(make-node empty human empty)]
    [(<= human-hight( **node-human-hight**))

I need to know how to access the hight field of the human object which will be within the node ( node-human-hight).

Upvotes: 1

Views: 91

Answers (2)

GoZoner
GoZoner

Reputation: 70275

Your insert-human-into-tree is going to need a bit more beyond the comparison to actually insert a new node. It will look something like this (which also answers your prime question):

(define (insert-human-into-tree human node)
  (if (empty? node)
      (make-node empty human empty)
      (let ((other (node-human node)))
        (cond ((< (human-height other) (human-height human))
               (insert-human-into-tree human (node-left node)))    ; go left
              ((> (human-height other) (human-height human))
               (insert-human-into-tree human (node-right node)))   ; go right
              (else ;; same height
                ...)))))

This will get you started.

Upvotes: 1

&#211;scar L&#243;pez
&#211;scar L&#243;pez

Reputation: 236170

Use the accessor procedures in the struct, for example:

(define-struct human(age hight))
(define james (make-human 10 50))
(define-struct node (left human right))

(define anode (make-node null james null))
; access the human in the node, and then the height of that human
(human-hight (node-human anode))
=> 50

... And it's spelled "height", not "hight". So, to answer the question, the comparison would look like this:

(<= (human-hight (node-human node)) (human-hight human))

Upvotes: 3

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