Sort a list of filenames alphabetically but grouped by their extension

Anu Anand Premji

I have a text file which goes like this:

apple.c
orange.hpp
plum.h
mango.c
banana.cpp
grapes.hpp

I want the above text sorted alphabetically but grouped based on their extensions: i.e,

apple.c
mango.c
banana.cpp
plum.h
grapes.hpp
orange.hpp

How can I do this in Notepad++?

guy038

Hello, Anu Anand Premji,

Very easily, indeed ! you just need two S/R, in regex mode and a classical sort :-))

So, from your original text, below :

apple.c
orange.hpp
plum.h
mango.c
banana.cpp
grapes.hpp

First, move back to the very beginning of your file, containing a list of filenames ( Ctrl + Home )
Open the Replace dialog ( Ctrl + H )
Select the Regular expression search mode
Fill up the two fields Find what: and Replace with:, with the values, below :

SEARCH (?-s)^.+\.(.+)

REPLACE \1\t\t$0

Click on the Replace all button

=> You should obtain the changed text, below :

c		apple.c
hpp		orange.hpp
h		plum.h
c		mango.c
cpp		banana.cpp
hpp		grapes.hpp

Now, perform a classical sort with the menu option Edit > Line operations > Sort Lines Lexicographically Ascending

=> We get the sorted text, below :

c		apple.c
c		mango.c
cpp		banana.cpp
h		plum.h
hpp		grapes.hpp
hpp		orange.hpp

Again, open the Replace dialog and type the regex expressions, below :

SEARCH (?-s)^.+\t+

REPLACE Leave the field EMPTY

Yeah ! Here is our final text, sorted as expected :-))

apple.c
mango.c
banana.cpp
plum.h
grapes.hpp
orange.hpp

I’ve got to be out for a while ! But, when I’m home, I’ll add some explanations to my regexes, just in case that you’re not acquainted with regular expressions !

Best Regards,

guy038

Anu Anand Premji

Wow!!! That worked perfectly!! Thank you!!
Saved me a lot of work!!

guy038

Hi Anu Anand Premji and All,

Well, I’m back home and here are some explanations on the two S/R :

The two search regex begin with the modifier (?-s) ( No PCRE_DOTALL ) that ensures that the regex engine will consider the dot special character . will match only a single standard character and not an EOL character
Then the part, ^.+\. matches, from the beginning of the current line ^, a maximum, NON empty, of characters, till a literal dot character ( which must be escaped by an antislash character \ in order to be considered as literal ) So, if the filename would be, for instance, “abc.def.ghi.cpp”, this range would be the string abc.def.ghi
The remainder of the search regex (.+) catches the remainder of the standard characters of the current line ( The extension part ) which is stored as group 1, due to the couple of parentheses
In replacement, the regex \1\t\t$0 rewrites the group 1 ( The extension part ), then two tabulation characters and, finally, the searched string, that is to say the name of each file, with its extension ( part $0 )
I preferred to use the tabulation character, instead of some spaces, because, with the tabulation character, the complete filenames look all aligned :-)
In the second S/R the part ^.+ selects, from the beginning of each line ^, the range maximum, NON empty, of standard characters, till a non empty range of tabulation characters \t+
As the replacement field is, this time, empty, all these characters, included tabulations , are, simply, deleted !

Cheers,

guuy038