Regular Expression list

Regex

Regular Expression  #use this link http://regexone.com/lesson/3 

1- 

match text 	abc123xyz 		?
match text 	define “123” 		?
match text 	var g = 123;

.*   -> . means select any character, *one or more character 
[a-z0-9]+ -> it will only cover abc123xyz because it will take any character between a-z and 0-9
[a-z \d]+ -> it will take any character between a-z and \d means take any digit 
abc123xyz, ^a.+ -> it will take any word which starts with a and then take anything 
[a-z\W0-9]+ -> it will all the match. 1 - a-z will cover all letters from a-z, \W any Non-Alphanumeric character, 0-9 means take number

2- your task 	text 		result
match text 	cat. 		?
match text 	896. 		?
match text 	?=+. 		?
skip text 	abc1 		?

.+\. -> . means match any character and "\." means overrides the matching of the period. You want to escape the dot from the sequence it you need to add this "\."

3- your task 	text 		result
match text 	can 		?
match text 	man 		?
match text 	fan 		?
skip text 	dan 		?
skip text 	ran 		?
skip text 	pan

[cmf] -> it will only find the words starting from c, m, f. can, man and fan will match here

4- Rakesh Ranjan Sukla 10/08/2015 

I just want to extract the the date field out from it
[0-9/]+ -> it will map only the date field and with '/' 

5- match text 	hog 		✓
   match text 	dog 		✓
   skip text 	bog 		✓

-> [hd] since it will only match hog and dog but not bog 

6- match text 	Ana 		✓
match text 	Bob 		✓
match text 	Cpc 		✓
skip text 	aax 		✓
skip text 	bby 		✓
skip text 	ccz 		✓

-> [^a-z] it will match any character except a-z. 
-> [ABC] it will match any character startwith ABC

7- if you want to match the number of repetition 

your task 	text 		result
match text 	wazzzzup 	 ✓
match text 	wazzzup 	 ✓
skip text 	wazup 		 ✓

-> z{2,4} this will map all the words where the z is repeated 2 to 4 times. {} is basically used for repetition 

8- your task 	text 		result
match text 	aaaabcc 		?
match text 	aabbbbc 		?
match text 	aacc                    ? 

-> .+ will match all the words but you should not use it 
-> [abc]+ it will also work 

9- your task 	text 		result
match text 	1 file found? 		?
match text 	2 files found? 		?
match text 	x files found? 		?

->  the pattern ab?c will match either the strings "abc" or "ac" because the b is considered optional
-> \w files? found\  this will be used to match such patters and files? will match files and file. 

10- your task 	text 		result
match text 	1. abc 		✓
match text 	2. abc 		✓
match text 	3. abc 		✓
skip text 	4.abc

-> \d\.\s+abc this will match all the patterns except 4.abc since there is no white space between the period and the number of characters.

11- your task 	text 		result
match text 	Mission: successful 		✓
skip text 	Last Mission: unsuccessful 		✓
skip text 	Next Mission: successful upon capture of target 	✓ 

-> ^Mission: successful$ this means that the word should start with Mission: and end with successful 
^ - it denotes the start of any string 
$ - it means the end of any string 

12- Match groups 

Well, in regular expressions we can accomplish this by grouping characters and capturing them using the special ( and ) (parenthesis) metacharacters. You can place any pattern inside the parenthesis to capture that part of the pattern. In our example above, the pattern ^(IMG\d+\.png)$ would capture the full filename from start to finish. If we had only wanted to capture the filename but not the extension, we could use ^(IMG\d+)\.png$ instead. 

your task 	text 	capture 	result
capture text 	file_a_record_file.pdf 	file_a_record_file 	✓
capture text 	file_yesterday.pdf 	file_yesterday 	✓
skip text 	testfile_fake.pdf.tmp 		✓

(\w+).pdf$ -> it will capture any alphanumeric character one or more than one and which 
() -> this is also known as the capture group 

13 - value.replace(/[^a-zA-Z0-9\n\.]/, " ")  replace all the special character in Open Refine