【笔记】正则表达式

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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()

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()

3.创建一个匹配对象,然后通过该对象获得匹配细节(Create an object with details about how the regex matches (part of) a string)

regex=ur”“ #正则表达式 match = re.search(regex, subject) if match:

match start: match.start()

match end (exclusive): atch.end()

matched text: match.group()

do_something() else: do_anotherthing()

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 = ””

  1. 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 = ””

  1. 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 = “”

  1. 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)

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): atch.end()

matched text: match.group()

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)

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()

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()

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): atch.end()

matched text: match.group()

do_something() else: do_anotherthing()

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 = ””

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 = ””

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 = ””

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)

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()

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 = re.sub(regex, newstring, subject)

2.替换所有匹配的子串(使用正则表达式对象)

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

字符串拆分

1.字符串拆分

result = re.split(regex, subject)

2.字符串拆分(使用正则表示式对象)

reobj = re.compile(regex)

result = reobj.split(subject)

Tag:正则表达式python Published under (CC) BY-NC-SA
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