Re module in python (1)

1. compile() function

Compiling regular expression patterns , Returns the pattern of an object （ You can compile those commonly used regular expressions into regular expression objects , It's a little bit more efficient ）.

Format ：

re.compile(pattern,flags=0)

for example ：

import re
text = "The moment you think about giving up,think of the reason why you held on so long."
text1 = "Life is a journey,not the destination,but the scenery along the should be and the mood at the view."
rr = re.compile(r'\w*o\w*')
print(rr.findall(text)) # lookup text All contained in 'o' 's words 
print(rr.findall(text1)) # lookup text1 All contained in 'o' 's words 

The operation results are as follows ：

['moment', 'you', 'about', 'of', 'reason', 'you', 'on', 'so', 'long']
['journey', 'not', 'destination', 'along', 'should', 'mood']

• pattern： Expression string used at compile time （ Regular expressions ）;
• flags：（ Optional ） Compile flag bit , Used to modify the matching method of regular expressions , Such as ： Is it case sensitive , Multiline matching, etc .

frequently-used flags Yes ：

sign meaning re.S(DOTALL) send . Match all characters including line breaks re.I（IGNORECASE） Make match match case insensitive re.L（LOCALE） Do localization identification （locale-aware) matching , French, etc re.M(MULTILINE) Multi-line matching , influence ^ and $re.X(VERBOSE) This flag is written in a more flexible format to make regular expressions easier to understand re.U according to Unicode Character set parsing characters , This sign affects \w,\W,\b,\B

2. match() function

Match at the beginning of the string , Matches the destination character at the beginning and returns , If there is no destination character at the beginning, the matching will fail , return None.

Format ：

re.match(pattern, string, flags=0)

for example ：

print(re.match('edu','educoder.net').group())
print(re.match('edu','www.educoder.net').group())

The operation results are as follows ：

notes ：match() The function returns a match object object , and match object The object has the following methods ：

• group()： Returns the regular matching string ;
• start()： Returns the position where the match started ;
• end()： Returns the position where the match ends ;
• span()： Returns a tuple containing a match ( Start , end ) The location of ;
• groups()： Returns the regular whole matching string , You can enter more than one group number at a time , The string matching the corresponding group number .

3. search() function

re.search() Function to find a pattern match in a string , Just find the first match and go back . If the string doesn't match , Then return to None.

Format ：

re.search(pattern, string, flags=0)

print(re.search('edu','www.educoderedu.net').group())
print(re.search('eduaaa','www.educoderedu.net').group())

The operation results are as follows ：

• notes ：match() and search() similar , The difference is match() Match only the beginning of the string , If the destination string does not appear at the beginning , Even if it appears later, it will not be matched ;search() Function will match within the whole character , As long as a destination string is found, it returns .