字符集

import re

s = 'abc, acc, adc, aec, afc, ahc'
# 找出中间是c或者f的单词

r = re.findall('a[cf]c',s) # 借助普通字符帮我们定界
print(r) # ['acc', 'afc']

# 找出中间不是c也不是f的单词

r = re.findall('a[^cf]c',s)
print(r) # ['abc', 'adc', 'aec', 'ahc']

r = re.findall('a[c-f]c',s) # 匹配c-f
print(r) #['acc', 'adc', 'aec', 'afc']