在Python的for循环中未激活Break [英] Break is not activated inside a for loop in Python

问题描述

我想从字典word_index中打印前10个键/值对，并编写了以下代码:

I want to print the first 10 key-value pairs from the dictionary word_index and I wrote this code:

for key, value in enumerate(word_index):
    count = 0
    if count <10:
        print(f'key {key} : value: {value}')
        count = count + 1
    else:
        break

如您所见，break未激活.这是为什么?我应该在代码中更改什么?

As you can see the break is not activated. Why is that? What I should change in the code?

推荐答案

您需要将count声明移至for循环之前.每次迭代都将其重置为0.

You need to move the declaration of count before the for loop. It is reset to 0 at each iteration.

作为一个旁注(我没有足够的声誉来发表评论)，for循环可能没有按照您的意愿做.您将变量命名为key和value，这使我相信您要遍历字典的条目(键和值对).为此，您应该编写:

As a side note (I don't have enough reputation to comment) the for loop is probably not doing what you want. You named your variables key and value, which makes me believe that you want to iterate over the entries (key and value pairs) of the dictionary. To achieve that you should write:

for k,v in word_index.items():
  // omitted

enumerate()的作用是返回一个从0开始的索引，并且该索引在每次迭代时都会递增.因此，在您的代码中，key实际上是一个索引，而value是字典的键！

What enumerate() does is to return an index that starts from 0 and it is incremented at each iteration. So the in your code, key is actually an index and value is the dictionary's key!

如果您实际上想遍历键并将索引与每个键相关联，则应将变量重命名为更正确的名称，例如index和key.

If you actually wanted to iterate over the keys and associate an index to each key, you should rename your variable to something more correct, for example index and key.

我建议花一些时间研究Python，它将为您节省大量调试时间.

I recommend to spend some time studying Python, it will save you lots of debugging time.

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