Question

运行此代码，我询问用户是否需要相反的代码。

一切运行顺利，但是当程序运行Do you want reverse order (y/n)部分时，由于某种原因，它会在下一行打印None？

任何人都可以解释为什么/如何让这个停止？

def farmList():
    print("Please enter six farming animals: ")
    terms = []
    for counter in range(6):
        term = input("Please enter a farm animal")
        terms.append(term)


    reverseOrder = input("Do you want reverse order (y/n)")
    if reverseOrder == "y":
        print(terms[::-1])
    else:
        print(terms)

    whichTerm = int(input("Choose a number between 1-6, and the program will print that animal: "))

    print(terms[whichTerm-1])

Answer 1

如果您正确调用farmList()，则将input更改为raw_input应适用于python 2.7。对于Python 2.7，raw_input()完全取用用户键入的内容并将其作为字符串传回。另外，对于Python 3，您的代码应该可以正常工作。

Answer 2

您的代码工作正常，至少在Python3中（有关详细信息，请参阅此主题：What's the difference between raw_input() and input() in python3.x）

请注意，您只显示反向列表，但不要反转terms：

Please enter six farming animals: 
Please enter a farm animala
Please enter a farm animalb
Please enter a farm animalc
Please enter a farm animald
Please enter a farm animale
Please enter a farm animalf
Do you want reverse order (y/n)y
['f', 'e', 'd', 'c', 'b', 'a']
Choose a number between 1-6, and the program will print that animal: 1
a

要反转您可以写的列表：

if reverseOrder == "y":
    terms = terms[::-1]

所以你的代码会变成：

def farmList():
    print("Please enter six farming animals: ")
    terms = []
    for counter in range(6):
        term = input("Please enter a farm animal")
        terms.append(term)


    reverseOrder = input("Do you want reverse order (y/n)")
    if reverseOrder == "y":
        terms = terms[::-1]

    whichTerm = int(input("Choose a number between 1-6, and the program will print that animal: "))

    print(terms[whichTerm-1])

farmList()

对于Python2.7，将input()的每次出现都替换为raw_input()。

当我运行它/ PYTHON时打印“无”

2 个答案: