Python正则表达式的用法

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)

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

result = re.split(regex, subject)

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

下面列出Python正则表达式的几种匹配用法：

regex=ur"..." #正则表达式
if re.search(regex, subject):
    do_something()
else:
    do_anotherthing()

regex=ur"...\Z" #正则表达式末尾以\Z结束
if re.match(regex, subject):
    do_something()
else:
    do_anotherthing()

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()

(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 = ""

(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 = ""

(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 = ""

(Get an array of all regex matches in a string)

result = re.findall(regex, subject)

(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()

(Create an object to use the same regex for many operations)

reobj = re.compile(regex)

（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()

（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()

（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()

（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 = ""

（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 = ""

（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 = ""

（Use regex object to get an array of all regex matches in a string）

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

（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()