Python：如何通过其索引引用字符串中的数字？

Question

I feel like this is a simple question, but it keeps escaping me...

If I had a string, say, "1010101", how would I refer to the first digit in the string by its index?

Answer 1

You can get the first element of any sequence with [0] . Since a string is a sequence of characters, you're looking for s[0] :

>>> s = "1010101"
>>> s[0]
'1'

For a detailed explanation, refer to the Python tutorial on strings .

Answer 2

负索引从右侧开始计数。

digit = mystring[-1]

Answer 3

In Python, a sting is something called, subscriptable . That means that you can access the different parts using square brackets, just like you can with a list.

• If you want to get the first character of the string, then you can simply use my_string[0] .

• If you need to get the last (character) in a string (the final 1 in the string you provided), then use my_string[-1] .

• If you originally have an int (or a long ) and you are looking for the last digit, you are best off using % (modulous) ( 10101 % 10 => 1 ).

• If you have a float, on the other hand, you are best of str(my_float)[-1]