Racket list in struct
- by Tim
I just started programming with Racket and now I have the following problem.
I have a struct with a list and I have to add up all prices in the list.
(define-struct item (name category price))
(define some-items
(list
(make-item "Book1" 'Book 40.97)
(make-item "Book2" 'Book 5.99)
(make-item "Book3" 'Book 20.60)
(make-item "Item" 'KitchenAccessory 2669.90)))
I know that I can return the price with: (item-price (first some-items)) or (item-price (car some-items)).
The problem is, that I dont know how I can add up all Items prices with this.
Answer to Óscar López:
May i filled the blanks not correctly, but Racket mark the code black when I press start and don't return anything.
(define (add-prices items)
(if (null? items)
(+ 0 items) ; Here I don't really know what to write for a 0.
; I tried differnt thnigs like null and this version.
(+ (item-price (first some-items))
(add-prices (item-price (rest some-items))))))
