Insert Single Character in Vim?

Thanks to Johnny for giving us this terrific answer in the comments below:

":nmap <C-i> i_<Esc>r"

That maps Control + i to insert a single character, and it does it very concisely.

In your vimrc file, this will look like:

nnoremap <C-i> i_<Esc>r

I changed my mapping to use space, and you can change yours to your preferred key(s):

nnoremap <Space> i_<Esc>r

MelBurslan is correct that this feature does not natively exist, but creating a user-defined command is not really the way to go about creating it. I tinkered for a few minutes and came up with this:

:nmap <silent> ,s "=nr2char(getchar())<cr>P

Which uses some Vim trickery involving "putting" text from a register, in this case the "expression" register. The expression being plugged into the register is "nr2char(getchar())" which will return a single character string.

The reason I built the mapping this way is that getting user input "midway through" a mapping is tricky and can behave unpredictably; even this mapping will drop the cursor down to the status area while waiting for the user to type a character.

As far as I know, there is no such function in any widely distributed incarnation of vi editor but, vim has a facility to create custom commands. It has previously been discussed here: in this thread

You might be able to create your custom command doing what you wish to do.

A simple way to do this is using the Cut x and Put p commands. Say that * is the character you want to insert. Insert it using i * Esc. Then hit x. That will cut the character. Now, you can hit p to put the single character. If you need to insert that character 300 times, you can type: 300p.