Python-交换函数-编程新手

Question

我是编程新手，正在学习 Python。我必须创建一个函数来交换列表中的 2 个索引。该列表已给出，但要交换的索引需要由用户输入。到目前为止，我已经能够想出这个...

def listSwap():
    print("This program will swap two indices within a list")
    myList = [3, 4, 2, 5, 1, 14, 23, 1]
    print("Here is your list... ", myList)
    index1 = eval(input("Pick an index from the list you would like to swap... "))
    index2 = eval(input("Now pick another index to swap with the first... "))

    tempIndex = index1
    myList[index1] = myList[index2]
    myList[index2] = myList[tempIndex]
    print("Here is your new list with swapped indices", myList)


def main():
    listSwap()

main()

但它并没有像我需要的那样工作。它将交换 1 个索引而不是另一个。 我能得到一些帮助吗？也许解释一下我做错了什么？

Answer 1

问题是您的代码本质上等于:

myList[index1] = myList[index2]
myList[index2] = myList[index1]

并且为索引使用第三个“临时”变量也无济于事。带有临时变量的正确版本如下所示:

temp = myList[index1]
myList[index1] = myList[index2]
myList[index2] = temp

但是，幸运的是，Python 有更优雅的交换值的方式:

myList[index1], myList[index2] = myList[index2], myList[index1]