Regular expressions - a practice

()　　　 Mark the beginning and end position of a sub-expressions .　　

Import Re 
A = ' { "name": "# WX #", "Sex": "# F #"} ' 
C = " (.? *) # # "  # match preceding expression 0 or 1 
y = the re.search (C, A)
 Print (y.group ())
 Print (y.group (. 1 ))

 ------------------------- - 
operating results 

# WX # 
WX

 

.　　　　 Matches any character (except newline)　

Import Re 
A = " # # kk12222foo " 
B = " . "   # matches any character 
S = the re.search (B, A)
 Print (s.group (0))

 ------------- --------------- 
operating results 

#

^　　　　Matches the beginning of the string　　

Import Re 
A = " # # kk12222foo " 
B = " ^ # "   # matches the beginning of the string 
S = the re.search (B, A)
 Print (s.group (0))

 ---------- ----------------- 
operating results 

#

$　　　　The end of the match the string　　

Import Re 
A = " # # kk12222foo " 
B = " # $ "   # end of the matched string 
S = the re.search (B, A)
 Print (s.group (0))

 ---------- ---------------- 
operating results 

#

*　　　　Match 0 or more times in front of the sub-expression appears

 

Import Re 
A = " # # kk12222foo " 
B = " . * "   # matches the previous expression 0 or more times this 
S = the re.search (B, A)
 Print (s.group (0))
 ----- ----------------------- 
operating results 

# kk12222foo #

 

+　　　　Match 1 or more times in front of the sub-expression appears

Import Re 
A = " # # kk12222foo " 
B = " 2+ "   # foregoing match expression 1 or more 
S = the re.search (B, A)
 Print (s.group (0))

 ----- ------------------- 
operating results

 2222

? Matches the preceding subexpression zero or one

Import Re 
A = " 44444, # # kk12222foo " 
C = " . 4? "  # Match preceding expression 0 or 1 
Y = the re.search (C, A)
 Print (y.group (0))

 --- ---------------------------- 
operating results


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