在Python 3中遍历数组 [英] Iterating over arrays in Python 3

问题描述

我已经有一段时间没有编码了，并试图重新使用Python.我正在尝试编写一个简单的程序，通过将每个数组元素值加到总和上来对数组求和.这就是我所拥有的:

I haven't been coding for awhile and trying to get back into Python. I'm trying to write a simple program that sums an array by adding each array element value to a sum. This is what I have:

def sumAnArray(ar):
    theSum = 0
    for i in ar:
        theSum = theSum + ar[i]
    print(theSum)
    return theSum

我收到以下错误:

line 13, theSum = theSum + ar[i]
IndexError: list index out of range

我发现我想做的事情显然像这样简单:

I found that what I'm trying to do is apparently as simple as this:

sum(ar)

但是很明显，无论如何我并没有正确地遍历数组，我认为这是我需要为其他目的而正确学习的东西.谢谢！

But clearly I'm not iterating through the array properly anyway, and I figure it's something I will need to learn properly for other purposes. Thanks!

推荐答案

像您一样在数组中循环时，for变量(在本示例中为i)是数组的当前元素.

When you loop in an array like you did, your for variable(in this example i) is current element of your array.

例如，如果您的ar是[1,5,10]，则每次迭代中的i值是1，5和10. 并且由于您的数组长度为3，因此可以使用的最大索引为2.因此，当i = 5时，您将得到IndexError. 您应该将代码更改为以下内容:

For example if your ar is [1,5,10], the i value in each iteration is 1, 5, and 10. And because your array length is 3, the maximum index you can use is 2. so when i = 5 you get IndexError. You should change your code into something like this:

for i in ar:
    theSum = theSum + i

或者，如果要使用索引，则应创建从0 ro array length - 1的范围.

Or if you want to use indexes, you should create a range from 0 ro array length - 1.

for i in range(len(ar)):
    theSum = theSum + ar[i]

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