is there a regex to add the line number in multiple places in the line?

Regular expressions cannot count (they have no concept of “increment a number”). Your two options inside Notepad++ are using the Column Editor like you’ve already discovered, or using a scripting plugin like PythonScript and using the full power of a programming language to influence the text in the open file. (I actually just answered a question earlier today on that same concept.)

apply it to different files with a different number of lines.

as linked in that other topic (and the links refenced there), you can make a macro that will do the begin/end-select for column mode… and if you combined that with other controls, like the Ctrl+Home to go to the start of the file, and Ctrl+End to go to the end, you could have a macro that does the zeroeth-column select in the macro, then manually type Alt+C to bring up the column editor and insert the numbers, then you could use another regex (using multiple capture groups) to distribute the number from the beginning of the line to the various locations throughout the line that you need

I’m doing it now using the column editor but I’d like to use it in a macro and apply it to different files with a different number of lines.

Here is a general solution which marks every word of File 1 ONLY IF this specific word is also present in File 2 :

MARK (?s-i)\b(\w+)\b(?=.+#####.+?\b\1\b)

So, for instance, from this initial text :

Ahmed:12321
12345,56789
Ali:22432
Khalid:567643
Alone sentence
Queen Elisabeth
This is a 789 test
ali
Mary Thompson
#####
Ahmed
Mary	789
Elisabeth
567643
test,a is:This

You would obtain, after the Mark process :

Ahmed:12321
12345,56789
Ali:22432
Khalid:567643
Alone sentence
Queen Elisabeth
This is a 789 test
ali
Mary Thompson
#####
Ahmed
Mary 789
Elisabeth
567643
test,a is:This

Notes :

• The words in File 2 can be in any order ;-)) I could have used :

#####
Mary	789 Ahmed
Elisabeth
567643
test
a
is!This

or even :

#####
Mary,a,789,is,Ahmed,Elisabeth,This,567643,test

• The present search is sensitive to case. If you prefer to search identical words, whatever their case, change the beginning of the regex from (?s-i) to (?si)

• By default, the part \b(\w+)\b looks for the greatest range of word characters, between 2 non-word chars. And a word character represents any single letter, accentuated letter, digit or the _ character. If you want to modify or add other characters to be considered as words, just go to Settings > Preferences... > Delimiter > Word character list

Best Regards,

guy038

(?-s)^(.+\R)(?=(?s).*#####.*?\1)

Change the (.+\R) to (.+?:).*?\R – everything else should stay the same