Regular expression

regex.py

,Regex summary and examples

. - any charcter except newline
\d - Digit(0-9)
\D - Not a digit(0-9)
\w - word charcter(a-z, A-Z,0-9,_)
\W- not a word charcter
\s - whitespace(space , tab, newline)
\S - not a whitespace(space , tab , newline)


\b - word boundry
\B - not a word boundry
^ - begining of a string
$ - end of string

[] - matches character in the bracket
[^ ]- matches charcter Not in the bracket 
| - Either or
() - Group

Quantifiers

* - 0 or more
+ - 1 or more
? - 0 or one
{3} - only particular char
{3-4} - range of characters  

. and \S works the same all characters or any characters

Examples:
  --------------------------------------------
  [email protected] y
[email protected]
[email protected]

^\w+(.|-)\w+(.|-)\w+[.|@]\w+[.|-]\w+.\w+[To fetch all above 3 or ]
[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+

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https://www.google.com
httpa://coreyms.com
http://youtube.com
https://www.nasa.gov

For above 3 url 1)[a-zA-Z]+2)[:]\/+3)[a-zA-Z.]+
1 for everything before :
2 for everything b/w : and //
3.for rest all

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Further work :read regex to match the words in reverse order
  
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Difference between re.match re.search re.fullmatch re.find re.findall re.finditer

re.match -->will attempt at the very first match (e.g re.match(r'abc','abcdefgabc') ==>it will give one group)
re.fullmatch --> will attempt the match for the entire string(e.g re.fullmatch(r'abc','abcdefgabc') ==>it will give two groups)
re.search -->will attempt the pattern through out the string
re.findall-->will attempt to search for pattern in the string and returns the result in a list of tuples
re.finditer -->will attept for loop

Link - https://www.youtube.com/watch?v=K8L6KVGG-7o&t=393s  (Python Tutorial: re Module - How to Write and Match Regular Expressions (Regex))
  
  
  Find IP address in a file or MAC
  import re
print "Hello World!\n" 
a = "fjmgdlmgn %10.12.32.12 iefjmvfkfkbm kb 2A.23.EE.TT"
p = re.findall("\w{2}\.\w{2}\.\w{2}\.\w{2}",a)
print(p)

ouyput
$python main.py
Hello World!

['10.12.32.12', '2A.23.EE.TT']