字符串索引超出范围时如何使字符串索引为圆形

Question

Suppose I have this string:

myString = 'abcdefghijklmnopqrstuvwxyz'

If I ask for myString[26], I will get an error saying string index out of range. Only myString[0] through myString[25] are valid.

My desired result is to ask for myString[26] and return 'a', because I have overreached the string by 1, and come back around front at 'a' in a circular motion. How can I achieve this?

Answer 1

Use modulo.

myString = 'abcdefghijklmnopqrstuvwxyz'

def access_char(string, i):
    return string[i % len(string)]

print(access_char(myString, 57))
# >>> f

This will also work for any other sequence datatype (list, tuple, etc.)

Answer 2

You just need to do myString[<index> % len(myString)] . <index> would be any integer that will be an index.

For example:

myString[26 % len(myString)]
>>> 'a'