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正则表达式是Python程序设计中非常实用的功能，本文就常用的正则表达式做一汇总，供大家参考之用。具体如下：
一、字符串替换
1.替换所有匹配的子串
用newstring替换subject中所有与正则表达式regex匹配的子串
result, number = re.subn(regex, newstring, subject)</div>
2.替换所有匹配的子串（使用正则表达式对象）
reobj = re.compile(regex) result, number = reobj.subn(newstring, subject)</div>
二、字符串拆分
1.字符串拆分
result = re.split(regex, subject)</div>
2.字符串拆分（使用正则表示式对象）
reobj = re.compile(regex) result = reobj.split(subject)</div>
三、匹配
下面列出Python正则表达式的几种匹配用法：
1.测试正则表达式是否匹配字符串的全部或部分
regex=ur"..." #正则表达式 if re.search(regex, subject): do_something() else: do_anotherthing()</div>
2.测试正则表达式是否匹配整个字符串
regex=ur"...\Z" #正则表达式末尾以\Z结束 if re.match(regex, subject): do_something() else: do_anotherthing()</div>
3. 创建一个匹配对象，然后通过该对象获得匹配细节
regex=ur"..." #正则表达式 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()</div>
4.获取正则表达式所匹配的子串
(Get the part of a string matched by the regex) regex=ur"..." #正则表达式 match = re.search(regex, subject) if match: result = match.group() else: result = ""</div>
5. 获取捕获组所匹配的子串
(Get the part of a string matched by a capturing group) regex=ur"..." #正则表达式 match = re.search(regex, subject) if match: result = match.group(1) else: result = ""</div>
6. 获取有名组所匹配的子串
(Get the part of a string matched by a named group)
regex=ur"..." #正则表达式
match = re.search(regex, subject)
if match:
result = match.group("groupname")
else:
result = ""
</div>
7. 将字符串中所有匹配的子串放入数组中
(Get an array of all regex matches in a string) result = re.findall(regex, subject)</div>
8.遍历所有匹配的子串
(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()</div>
9.通过正则表达式字符串创建一个正则表达式对象
(Create an object to use the same regex for many operations) reobj = re.compile(regex)</div>
10.用法１的正则表达式对象版本
(use regex object for if/else branch whether (part of) a string can be matched) reobj = re.compile(regex) if reobj.search(subject): do_something() else: do_anotherthing()</div>
11.用法２的正则表达式对象版本
(use regex object for if/else branch whether a string can be matched entirely) reobj = re.compile(r"\Z") #正则表达式末尾以\Z 结束 if reobj.match(subject): do_something() else: do_anotherthing()</div>
12.创建一个正则表达式对象，然后通过该对象获得匹配细节
(Create an object with details about how the regex object matches (part of) a string) reobj = re.compile(regex) match = reobj.search(subject) if match: # match start: match.start() # match end (exclusive): match.end() # matched text: match.group() do_something() else: do_anotherthing()</div>
13.用正则表达式对象获取匹配子串
(Use regex object to get the part of a string matched by the regex) reobj = re.compile(regex) match = reobj.search(subject) if match: result = match.group() else: result = ""</div>
14.用正则表达式对象获取捕获组所匹配的子串
(Use regex object to get the part of a string matched by a capturing group) reobj = re.compile(regex) match = reobj.search(subject) if match: result = match.group(1) else: result = ""</div>
15.用正则表达式对象获取有名组所匹配的子串
(Use regex object to get the part of a string matched by a named group)
reobj = re.compile(regex)
match = reobj.search(subject)
if match:
result = match.group("groupname")
else:
result = ""
</div>
16.用正则表达式对象获取所有匹配子串并放入数组
(Use regex object to get an array of all regex matches in a string) reobj = re.compile(regex) result = reobj.findall(subject)</div>
17.通过正则表达式对象遍历所有匹配子串
(Use regex object to iterate over all matches in a string) reobj = re.compile(regex) for match in reobj.finditer(subject): # match start: match.start() # match end (exclusive): match.end() # matched text: match.group()</div>
感兴趣的读者可以动手调试一下本文实例代码，相信会有新的收获。
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