Question

我想编写一个在Prolog中返回更改的程序，我尝试了这个谓词，但我不确定它，因为我想要像在C / C ++程序中那样做。如果有人对此进行了更正，我会很感激。

dollar(100).
quarter(25).
dime(1).


return(0,0,0).
return(Amount_recieved,Amount_due,Change) :-
   Change is Amount_recieved - Amount_due.

dollar(100) is Change / 100 , Change is Change mod 100.
quarter(25) is Change /25 , Change is Change mod 25.
dime(1) is Change

Answer 1

我提出以下基于结构amount/3的解决方案，其中包含美元数（第一个值），季度数（第二个值）和角钱数（第三个值）

getAmountInDimes(amount(Do, Qu, Di), AmountInDimes) :-
  AmountInDimes is (Do * 100) + (Qu * 25) + Di.

getAmountTriple(AmountInDimes, amount(Do, Qu, Di)) :-
  Do  is AmountInDimes div 100,
  Mid is AmountInDimes mod 100,
  Qu  is Mid div 25,
  Di  is Mid mod 25.

computeChange(AReceived, ADue, Change) :- 
  getAmountInDimes(AReceived, ARDimes),
  getAmountInDimes(ADue, ADDimes),
  ARDimes >= ADDimes,
  CDimes is ARDimes - ADDimes,
  getAmountTriple(CDimes, Change).

以下是使用示例

computeChange(amount(20, 0, 0), amount(15, 2, 12), Ch)

将Ch与amount(4,1,13)统一起来。

另一个例子

computeChange(amount(20, 0, 0), amount(15, 2, 12), amount(Do, Qu, Di))

直接将Do与4，Qu与1和Di与13直接统一。

Prolog中的程序返回更改

1 个答案: