the other regular expression.txt

this is a list of regular expression to extract ASCII or replace non ascii

#extract ascii
[ -~]+

#replace non ascii
[^\t\r\n\x20-\x7E]+

#replace non ascii
[^a-z0-9``~!@#$%^&*()\-_=+\[\]{}\\|;:'"<>,./?\r\n]+

#extract ascii
[a-zA-Z0-9~@#\^\$&\*\(\)-_\+=\[\]\{\}\|\\,\.\?\s]+

#replace non ascii
[^a-zA-Z0-9~@#\^\$&\*\(\)-_\+=\[\]\{\}\|\\,\.\?\s]+

#replace non ascii in Hexadecimal
[^\\x00-\\xFFFF]+\\[a-z]\d.*?  
https://regex101.com/r/LGGbNy/1/

#select a character every specific number of character    [change {1} to the specific number of character that you want]
(?:([\w])){1}(?1)\K
https://regex101.com/r/8ASqoV/1


preceding means the pattern before the quantifiers 
quantifiers are always at the end of the pattern, but that does not mean at the end of the whole regex pattern

+		Matches its preceding pattern for one or more number of times.  				[does care for pattern/character before it (greedy)]
*		Matches its preceding pattern for zero or more number of times. 				[does not care for pattern/character before it (greedy)]
?		Matches its preceding pattern for zero or one number of times.  				[does not care for pattern/character before it (lazy)]
{n}		Matches its preceding pattern exactly for n number of times.
{m,n}	Matches its preceding pattern for m to n number of times.
{n,}	Matches its preceding pattern for n or more number of times.

you can set a minimum without a maximum but don't forget the comma

custom ranged quantifiers is like Division in math
.{5,6}
(.) means any character and {} is {min,max} 
min is the minimum number of to be selected
max is the maximum number of to be selected
the number of characters will be divided by max and if there is a remainder it will not be selected if [remainder < minimum] 
{5}is the same as {5,5} it is both minimum and maximum at the same time

any character before the quantifier will be considered as a rule for the quantifier. And at the same time the whole string will be considered as string to match, and the match will only happen when these two rules intersect

the behaviour will change if you put the string before the quantifier inside []
The quantifier will treat anything inside [] as a separate character

the behaviour will change if you put the string before the quantifier inside ()
The quantifier will treat anything inside () as a whole string


#Boundaries
\b word boundary
https://i.imgur.com/pEWyQl2.png

\B non-word boundary
https://i.imgur.com/oKXMJda.png