String模块中的常量:
string.digits:数字0~9
string.letters:所有字母(大小写)
string.lowercase:所有小写字母
string.printable:可打印字符的字符串
string.punctuation:所有标点
string.uppercase:所有大写字母
From https://blog.csdn.net/sheila_1988/article/details/7243256>>> import string >>> string.digits '0123456789' >>> string.letters 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz' >>> string.lowercase 'abcdefghijklmnopqrstuvwxyz' >>> string.printable '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~ \t\n\r\x0b\x0c' >>> string.punctuation '!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~' >>> string.uppercase 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'