使用正则表达式:^[2|4]\d?$
解释:
示例代码:
import re
pattern = "^[2|4]\d?$"
print(re.match(pattern, "3")) # None print(re.match(pattern, "23")) # Match print(re.match(pattern, "26")) # None print(re.match(pattern, "4")) # Match print(re.match(pattern, "40")) # Match print(re.match(pattern, "41")) # None