TypeError：“分数”类型的对象没有 len()

Question

我已对其进行了调整以将 self 添加到更新中，但现在我在测试内容时遇到了问题。

from file import Fraction
import random
def main():
    a = Fraction()
    b = a.update()
main()

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我正在尝试使这个 for 循环工作，它应该将列表的第一个数字减去第二个，第二个减去第三个等，并使用这些值创建一个新列表。 __init__ 部分有效，但更新功能是我遇到麻烦的地方。

class Fraction():
    def __init__(self):
        shape = int(input("How many sides does the shape have? : "))
        if shape <= 0: #doesnt work with negatives?
            print("Please make a valid choice (positive integers only)")
            shape = int(input("How many sides does the shape have? : "))
        numbers = 0
        print("Your numbers are: ")
        numbers = []
        for i in range(0,shape):
            n = random.randint(1,100)
            numbers.append(n)
        print(numbers)

    def update(numbers):
        long=len(numbers)
        for i in range(long):
            newnum = numbers[i]-numbers[i+1]

        print(newnum)

Answer 1

您必须使用self.number 才能访问update 中的号码。你应该在def update(number)中使用self而不是number

此外，要创建新列表，您必须在 for-loop 和 append(newnum) 之前创建空列表到此列表。之后你可以return这个列表获取它为b = ...

class Fraction():

    def __init__(self):
        shape = int(input("How many sides does the shape have? : "))

        if shape <= 0: #doesnt work with negatives?
            print("Please make a valid choice (positive integers only)")
            shape = int(input("How many sides does the shape have? : "))

        self.numbers = []
        for i in range(shape):
            n = random.randint(1, 100)
            self.numbers.append(n)
        print("Your numbers are:", self.numbers)

    def update(self):
        newlist = []

        long = len(self.numbers)
        for i in range(long-1): # it has to be long-1 because later `long-1+1`will give `long` 
            newnum = self.numbers[i] - self.numbers[i+1]
            newlist.append(newnum)

        return newlist

import random

def main():
    a = Fraction()
    b = a.update()
    print(b)
main()

---

顺便说一句：最好在类外使用input() 并将其作为Fraction(shape) 运行，这样它就可以使用input() 或文件或硬编码变量中的值运行。使用相同的值一次又一次地测试代码是有帮助的。