python怎样遍历字符串

strs = 'abcd'

for ch in strs:

    print(ch)

strs = 'abcd'

for index, ch in enumerate(strs):

    print(index,end=' ')

    print(ch)

strs = 'abcd'

for index in range(len(strs)):

    print(strs[index], end=' ')

strs = 'abcd'

for ch in iter(strs):

    print(ch)