管道可以匹配多個正則表達式中的一個
>>>
>>> m=re.search(r'Batman|Tina Fey','Batman and Tina Fey')
>>> print(m.group())
Batman
>>> m=re.search(r'Batman|Tina Fey','Tina Fey and Batman')
>>> print(m.group())
Tina Fey
>>>
問號表明它前面的字符或分組在這個模式中是可選的，匹配“零次或一次"
>>> batRegex=re.compile(r'Bat(wo)?man')
>>> m1=batRegex.search('I am a Batman')
>>> print(m1.group())
Batman
>>> m2=batRegex.search('I am a Batwoman')
>>> print(m2.group())
Batwoman
>>>
在上述正則表達式中wo是可選的，既可以匹配Batman，又可以匹配Batwoman
>>>
>>> phoneRegex=re.compile(r'(\d{3}-)?\d{3}-\d{4}')
>>> m1=phoneRegex.search('My phone number is 021-456-2345')
>>> print(m1.group())
021-456-2345
>>> m2=phoneRegex.search('My phone number is 456-2345')
>>> print(m2.group())
456-2345
>>>
上面的正則表達式匹配的電話號碼可以帶區號，也可以不帶區號
星號意味着“匹配零次或者多次”
>>>
>>> batRegex=re.compile(r'Bat(wo)*man')
>>> m=batRegex.search('I am a Batman')
>>> print(m.group())
Batman
>>> m=batRegex.search('I am a Batwoman')
>>> print(m.group())
Batwoman
>>> m=batRegex.search('I am a Batwowoman')
>>> print(m.group())
Batwowoman
>>>
加號意味着“匹配一次或多次”
>>>
>>> batRegex=re.compile(r'Bat(wo)+man')
>>> m=batRegex.search('I am a Batwoman')
>>> print(m.group())
Batwoman
>>> m=batRegex.search('I am a Batwowoman')
>>> print(m.group())
Batwowoman
>>> m=batRegex.search('I am a Batman')
>>> m == None
True
>>>
花括號匹配特定次數
(ha){2}匹配‘haha’
(ha){2,}匹配2次或更多次ha
(ha){.2}匹配0到2次ha
(ha){2.5}匹配2到5次ha