第17 步：为什么 while 循环不是无限的？让我们仔细看看使用error和r测试用例。
while循环不是无限的，因为我们用.upper()大写错误地更改了每个r ！每次循环运行时，它都会找到一个r并将其更改为R 。最终，所有的r都变成了R 。对于条件， r与R不同。最终r不再出现在单词eRRoR中，这导致循环停止！
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第17 步：为什么 while 循环不是无限的？让我们仔细看看使用error和r测试用例。
while循环不是无限的，因为我们用.upper()大写错误地更改了每个r ！每次循环运行时，它都会找到一个r并将其更改为R 。最终，所有的r都变成了R 。对于条件， r与R不同。最终r不再出现在单词eRRoR中，这导致循环停止！
To navigate the page using the TAB key, first press ESC to exit the code editor.
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Warning: This will erase any existing program on your micro:bit.
Having trouble? Check out the micro:bit instructions to update your firmware.
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