折扣功能不起作用

Question

%b is for Boolean
%f is for Decimal floating-point
%c is for Character
%d is for Decimal integer
%s is for String

我无法使用折扣功能工作，使用tkinter进行python 3.4。

这个功能应该给予折扣，如果顾客买了5个甜甜圈，他们会免费获得一个。

Answer 1

这就是你计算我相信的方式：

示例：

def discount(p, n, f=0):
    """Calculate discount as a percentage (given as a float)
       given:

       (p)rice
       (n)umber
       (f)ree
    """

    total_bought = float(p * n)
    total_free = float(p * f)

    return 1.0 / (total_bought / total_free)

<强>演示：

>>> discount(1, 5, 1)
0.2  # 20% discount
>>> discount(1, 5, 2)
0.4  # 40% discount
>>> discount(1, 6, 3)
0.5  # 50% discount
>>> discount(1, 6, 6)
1.0  # 100% discount