Pretty new to mappings in Vim,

In Diff Mode I've got C-Up and C-Down mapped to [c and ]c for diffjumping. I'm wanting to map C-Right and C-Left to :<C-U>diffput v:count<CR> and :<C-U>diffget v:count<CR> respectively to speed up merging.

nnoremap <C-Left> :<C-U>diffget v:count<CR>
nnoremap <C-Right> :<C-U>diffput v:count<CR>
nnoremap <C-Up> [c
nnoremap <C-Down> ]c

This should.... put from buffer # or get from buffer #.

But I get the error "no matching buffer for v:count".

the command looks to be taking v:count literally and running :diffget v:count instead of :diffget 3 for example.. how do I get v:count to resolve to a number? like dereference the variable?

I can echo "diffget v:count" and that looks to be correct... but obviously doesn't do anything...

  • 1
    The right-hand side is the literal text you would type; as you already figured our it's not evaluated. To evaluate VimScript in there you can use an expression mapping by adding <expr>: nnoremap <expr> <C-Left> ":\<C-U>diffget " .. v:count .. "\<CR>". Didn't test that so may not work exactly, but should point you in the right direction. Note that because it's a VimScript expression, you need to put literal text in strings. Special <..> only work in double-quoted strings as "\<..>". Apr 1, 2022 at 12:19
  • @MartinTournoij Worked Perfectly! Thanks - learning slowly! :) don't know how to add mark a comment as the answer..
    – Jack T
    Apr 1, 2022 at 12:28
  • What is the purpose of the " .. " if you don't mind explaining? Looks like concat for strings?
    – Jack T
    Apr 1, 2022 at 12:29
  • Well, you're not really supposed to answer questions in comments, so you can't accept it 😅 As for the .., that's indeed just string concatenation. Actually just . also works, but .. is the "new" way of doing it (it solves some ambiguity in some cases with . for other uses like decimals in numbers). Apr 1, 2022 at 12:32
  • Thanks @MartinTournoij you're so helpful.
    – Jack T
    Apr 1, 2022 at 13:06

1 Answer 1


Instead of using <expr> as suggested in the comments, I would first try

nnoremap <C-Left> :<C-u>execute 'diffget' v:count<CR>

as in How do I use a variable or return value in option, command, or mapping?

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