正則表達式是Python程序設計中非常實用的功能，本文就常用的正則表達式做一匯總，供大家參考之用。具體如下：

一、字符串替換

1.替換所有匹配的子串

用newstring替換subject中所有與正則表達式regex匹配的子串

result, number = re.subn(regex, newstring, subject)

2.替換所有匹配的子串（使用正則表達式對象）

reobj = re.compile(regex)result, number = reobj.subn(newstring, subject)

二、字符串拆分

1.字符串拆分

result = re.split(regex, subject)

2.字符串拆分（使用正則表示式對象）

reobj = re.compile(regex)result = reobj.split(subject)

三、匹配

下面列出Python正則表達式的幾種匹配用法：

1.測試正則表達式是否匹配字符串的全部或部分

regex=ur"..." #正則表達式if re.search(regex, subject):  do_something()else:  do_anotherthing()

2.測試正則表達式是否匹配整個字符串

regex=ur".../Z" #正則表達式末尾以/Z結束if re.match(regex, subject):  do_something()else:  do_anotherthing()

3. 創建一個匹配對象，然后通過該對象獲得匹配細節

regex=ur"..." #正則表達式match = re.search(regex, subject)if match:  # match start: match.start()  # match end (exclusive): match.end()  # matched text: match.group()  do_something()else:  do_anotherthing()

4.獲取正則表達式所匹配的子串

(Get the part of a string matched by the regex)regex=ur"..." #正則表達式match = re.search(regex, subject)if match:  result = match.group()else:  result = ""

5. 獲取捕獲組所匹配的子串

(Get the part of a string matched by a capturing group)regex=ur"..." #正則表達式match = re.search(regex, subject)if match:  result = match.group(1)else:  result = ""

6. 獲取有名組所匹配的子串

(Get the part of a string matched by a named group)regex=ur"..." #正則表達式match = re.search(regex, subject)if match:  result = match.group("groupname")else:  result = ""

7. 將字符串中所有匹配的子串放入數組中

(Get an array of all regex matches in a string)result = re.findall(regex, subject)

8.遍歷所有匹配的子串

(Iterate over all matches in a string)for match in re.finditer(r"<(.*?)/s*.*?//1>", subject)  # match start: match.start()  # match end (exclusive): match.end()  # matched text: match.group()

9.通過正則表達式字符串創建一個正則表達式對象

(Create an object to use the same regex for many operations)reobj = re.compile(regex)