这是我的代码:
# B. both_ends
# Given a string s, return a string made of the first 2
# and the last 2 chars of the original string,
# so 'spring' yields 'spng'. However, if the string length
# is less than 2, return instead the empty string.
def both_ends(s):
if len(s) <= 2:
return ""
else:
return s[0] + s[1] + s[len(s)-2] + s[len(s-1)]
# +++your code here+++
return
不幸的是我的程序没有运行。 :( 我确定我忽略了一些东西，因为我是 Python 的新手。
这是错误:
> Traceback (most recent call last):
File "C:\Users\Sergio\Desktop\google-python-exercises\google-python-exercises\basic\string1.py", line 120, in <module>
main()
File "C:\Users\Sergio\Desktop\google-python-exercises\google-python-exercises\basic\string1.py", line 97, in main
test(both_ends('spring'), 'spng')
File "C:\Users\Sergio\Desktop\google-python-exercises\google-python-exercises\basic\string1.py", line 44, in both_ends
return s[0] + s[1] + s[len(s)-2] + s[len(s-1)]
TypeError: unsupported operand type(s) for -: 'str' and 'int'
谢谢大家的帮助。 :D
请您参考如下方法:
错位的括号:
return s[0] + s[1] + s[len(s)-2] + s[len(s)-1]
顺便说一句:
return s[0] + s[1] + s[-2] + s[-1]
或
return s[:2] + s[-2:]
