How to replace bytes \xe3\x80\x80 with byte \x20 in vim? - vim

Question

Let's to create target file to operate with.
python3
>>> mfile = open("f:/test.txt","wb")
>>> mfile.write(b'\xe3\x80\x80')
3
>>> mfile.close()
Now to open f:/test.txt with xxd,you will see three bytes \xe3\x80\x80 in it,our target file encoding with utf-8 contains three bytes \xe3\x80\x80.
python3
b'\xe3\x80\x80'.decode('utf-8')
'\u3000'
It means that the unicode of three bytes in test.txt encoding with utf-8 is 3000.
:s/\%u3000/ /g
s/\%u3000/ /g can replace bytes \xe3\x80\x80 with byte \x20 in vim.
Issue remains still here.
:s/\%u3000/\%u20/g
:s/\%u3000/\%x20/g
:s/\%u3000/\x20/g
All the three formats above here can't work,why \xe3\x80\x80 can be expressed by \%u3000 in vim, (white blank) can't be expressed by \%u20 or \%x20 or \x20 ?
can express \x20, white blank is printable character,what's more, i want to replace the three bytes \xe3\x80\x80 with latin-1's nbsp?
The nbsp in latin-1 encoding means Non-breaking space which is NON PRINTABLE CHARACTERS,how to write the expression in vim?
:s/\%u3000/\%ua0/g
:s/\%u3000/\%xa0/g
:s/\%u3000/\xa0/g
None of them can work for the case.

Answer 1

You can type the \xe3\x80\x80 or u3000 character by pressing ctrl+v then u and then the 4 Unicode characters, in your case 3000 (check :help i_CTRL-V_digit ), since is a black character you will see nothing but just a space, you could type :set list to see all the places where you have that character or in any case add this to your .vimrc
set listchars=tab:▸\ ,eol:¬,trail:·,extends:#,nbsp:.
Now in the same way you enter the character, you could try to replace it within the command line, but in this case to be available to enter the ctrl+v you could try using the command-line window (:help cedit).
Go to command mode and after having the : press ctrl+f it will open the command-line window in where you could go into insert mode and type: %s/ctrl+vu3000/ /g and when done press enter to apply command.
Give a try first before entering the command-line window, since when using ctrl+v it may work, not like when using ctrl+k (http://vim.wikia.com/wiki/Entering_special_characters)
In the image instead of replacing with a white space / /, Is replacing with ---- just to visually see the changes.

Answer 2

1.How to input non printable characters when to edit a file in vim?
In the insert mode:
1.ctrl+v (ctrl+q if ctrl+v call paste from regitor)
2.input u
3.input the unicode value of non printable characters
4.input enter key
2.How to input non printable characters in substitute command of vim's ex mode?
For example, to replace all bytes \xe3\x80\x80 with \xa0,all byte's encoding is utf-8.
1. get the byte's unicode value
`\xe3\x80\x80`'s unicode value is `3000`,
`\xa0`'s unicode value is `a0`.
2.press `:` into ex mode.
3.:s/\%u3000/
4:ctrl+v ua0
do not input enter as above process
5.go on to input `/g`.
6.press enter.