判断为什么都是True？

Question

a = "aa123"b = "11111"c = "aaaaa"print(a.isalnum())print(b.isalnum())print(b.isalnum())输出/python/ex7# python d6.py TrueTrueTrue应该是TrueFalseFalse才对吧，是不是python版本不行？python 版本号Python 2.6.4rc2 (r264rc2:75497, Oct 20 2009, 02:55:11)

Answer 1

s=input("please inupt string")
print(s.isdigit()) #用isdigit函数判断是否数字
print(s.isalpha()) #isalpha判断是否字母
print(not (s.isalpha() or s.isdigit()) and s.isalnum()) #isalnum判断是否数字和字母的组合