Python regular expression to determine if a string is all lowercase examples

Copy CodeThe code is as follows:

#-*-coding:cp936-*-
Import re
S1 = ' ADKKDK '
S2 = ' ABC123EFG '

an = Re.search (' ^[a-z]+$ ', S1)
If an:
print ' S1: ', An.group (), ' all lowercase '
Else
Print S1, "Not all lowercase!" "

an = Re.match (' [a-z]+$ ', S2)
If an:
print ' s2: ', An.group (), ' all lowercase '
Else
Print S2, "Not all lowercase!" "

1. Regular expressions are not part of Python and need to refer to the RE module when used

2. The matching form is: Re.search (regular expression, with matching string) or re.match (regular expression, with matching string). The difference is that the latter begins with the start character (^) by default. So

Re.search (' ^[a-z]+$ ', S1) is equivalent to Re.match (' [a-z]+$ ', S2)
3. If the match fails, an = Re.search (' ^[a-z]+$ ', S1) returns none

Group is used to group matching results

Copy the Code code as follows:

Import re
A = "123abc456"
Print Re.search ([[0-9]*] ([a-z]*) ([0-9]*)], a). Group (0) #123abc456, return to the whole
Print Re.search ("([0-9]*) ([a-z]*) ([0-9]*)", a). Group (1) #123
Print Re.search ("([0-9]*) ([a-z]*) ([0-9]*)", a). Group (2) #abc
Print Re.search ("([0-9]*) ([a-z]*) ([0-9]*)", a). Group (3) #456

1) Three sets of parentheses in regular expressions divide matching results into three groups

Group () with group (0) is the overall result of matching regular expressions

Group (1) lists the first bracket matching section, Group (2) lists the second bracket matching part, and group (3) lists the third bracket matching part.

2) No match succeeded, Re.search () return None

3) Of course there are no brackets in the Zheng expression, and group (1) must be wrong.

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