为什么 'aa' < 'z' 在 Python 中的计算结果为 True？

Question

I am working with string comparison in Python. Why does 'aa' < 'z' evaluate to True. Further, why does 'aa' < 'a' evaluate to False. I tried explaining 'aa' is of a longer length than 'a' so it would be greater. But this reasoning does not work for the initial case 'aa' < 'z'

'aa' < 'z' => True 'aa' < 'a' => False

Answer 1

String comparisons use lexicographical order. To put it in simple terms, it's the order in which words would appear in a dictionary. Your examples would look like this:

a
aa
z

And clearly 'a' < 'aa' is True as well as 'aa' < 'z' . If two words consist of the same character repeated several times, the shortest word would go first. For the rest, it's just the order of the alphabet.

Answer 2

They're in dictionary order. Alphabetical order first, length as a tie breaker. Just like in a dictionary, a precedes aa which precedes z .

Answer 3

I think, you can help the function ord() to understand it. https://www.programiz.com/python-programming/methods/built-in/ord

If see your example 'aa' < 'a' => False first symbol from 'aa' have an integer representing the Unicode character 97 and result 97 < 97 => False . If we see next your example 'aa' < 'z' => True. Python see only first symbol like this 'a' < 'z' == 97 < 122 => True .

I hope I can help you!