Understand Regular Expression

Character	Description
\w	Matches any word character (alphanumeric).
\W	Matches any non-word character.
\s	Matches any whitespace character (tab, newline, carriage return, form feed, vertical tab).
\S	Matches any non-whitespace character.
\d	Matches any numerical digit.
\D	Matches any character that is not a number.
[\b]	Matches a backspace.
.	Matches any character except a newline.
[...]	Matches any one character within the brackets.
[^...]	Matches any one character not within the brackets.
[x-y]	Matches any character in the range of x to y.
[^x-y]	Matches any character not in the range of x to y.
{x,y}	Matches the previous item at least x times but not to exceed y times.
{x,}	Matches the previous item at least x times.
{x}	Matches the previous item exactly x times.
?	Matches the previous item once or not at all.
+	Matches the previous item at least once.
*	Matches the previous item any number of times or not at all.
|	Matches the expression to the left or the right of the | character.
(...)	Group everything inside parentheses into a subpattern.
\x	Matches the same characters that resulted from the subpattern in group number x. Groups, which are designated with parentheses, are numbered from left to right.
^	Matches the beginning of the string or beginning of a line, in multiline matches.
$	Matches the end of the string or end of a line, in multiline matches.
\b	Matches the position between a word character and a non-word character.
\B	Matches the position that is not between a word character and a non-word character.

Know More in Regular Expression
Character	Description
\f	Form feed
\n	Newline
\r	Carriage return
\t	Tab
\v	Vertical tab
\/	Forward slash (/)
\\	Backward slash (\)
\.	Period (.)
\*	Asterisk (*)
\+	Plus (+)
\?	Question Mark (?)
\|	Horizontal bar (|)
\(	Left parenthesis (
\)	Right parenthesis )
\[	Left bracket ([)
\]	Right bracket (])
\{	Left curly brace ({)
\}	Right curly brace (})
\XXX	ASCII character represented by the octal number XXX
\xHH	ASCII character represented by the hexadecimal number HH
\cX	The control character represented by X

Regular Expressions in PHP

Regular Expression
Regex is used to match any pattern against any string
Its use for pattern matching
Its very powerful but use only in extreme case (Increase the lookup time)

wild card -> . $ * ^ + ? |
match scope -> () {} []

regex vs string/array functions ->
preg_match() ->
preg_replace() ->
preg_split() ->
preg_grep() ->

What i Learn in Notepad++

Replace Duplicate Rows
^(.*?)$\s+?^(?=.*^\1$)

Replace Blank Rows
[\r\n]+

New Rows
\r\n

Replace Content between 2 anchor Tags
</a>.*?<a
</a>\r\n<a

Replace Brakets Inside Content
\{[^{}]*\} replace with space

Insert Something Vertically
ALT+C

Convert to Uppercase
CTRL+SHIFT+U

Resources
http://www.shortcutworld.com/en/win/Notepad-plus-plus_5.9.html
http://letconex.blogspot.in/2013/06/how-to-use-regular-expressions-in.html

http://www.iacquire.com/blog/18-meta-tags-every-webpage-should-have-in-2013

MSWORD Wild Card
http://www.gmayor.com/replace_using_wildcards.htm
http://superuser.com/questions/290618/subscripts-and-superscripts-in-excel

Special Char Codes
http://www.utexas.edu/learn/html/spchar.html