Convert first lowercase to uppercase and uppercase to lowercase (regex?)

问题

I have a huge file in this layout:

world12345:Betaalpha    
world12344:alphabeta    
world12343:ZetaBeta    
world12342:!betatheta

I need to convert the first lowercase letter after the ":" to uppercase and the first uppercase letter to lowercase. I've tried using notepad++ and emeditor, but I'm not that experienced with regex.

This is how I want it to become after (regex?)

world12345:betaalpha    
world12344:Alphabeta    
world12343:zetaBeta    
world12342:!betatheta   (unchanged, as the first char is a special char)

I have tried searching the web for a regex in npp+, but to no avail. Unfortunately, I'm not a scripter so I can't write one myself.

Thanks in advance!

回答1:

Thanks to this answer, I was able to find a solution to your problem after initially thinking it wasn't possible.

The way to do this in Notepad++ is to use the following options:

Open the Replace dialog (Ctrl + H)
Find what: ^([^:]+:)(([A-Z])|([a-z]))([^:]+)$
Replace with: $1\L$3\E\U$4\E$5
Check Match case
Check Wrap around
Select Regular expression
Uncheck . matches newline
Press Replace All

Here's a GIF of this in action:

The breakdown of the Find what field:

^ at the front of the Regular Expression represents the beginning of a line and $ at the end represents the end of a line. This prevents it from being lazy or wrapping to the next line.
([^:]+:) represents the characters at the beginning of the line, allowing all characters except :. This is group $1
(([A-Z])|([a-z])) represents the first character after the :. If there is anything other than an upper or lowercase letter, it will skip the line.
- Group $2 will be the first character, regardless of uppercase or lowercase. We'll ignore this in our replacement.
- Group $3 will be the first character if it is uppercase, otherwise $3 will be empty.
- Group $4 will be the first character if it is lowercase, otherwise $4 will be empty.
([^:]+) represents the characters at the end of the line, allowing all characters except :. This is group $5.

The breakdown of the Replace with field:

$1 will be the first group as described above
\L$3\E will convert group $3 as described above to lowercase.
\U$4\E' will convert group$4` as described above to uppercase.
$5 will be the last group as described above

\L and \U stand for "beginning converting to lowercase" or "uppercase," respectively. \E stands for "stop converting." Since only one out of $3 or $4 will contain the first character (the other will be blank), this converts only in the case we want.