Question

I am dealing with a block of comments like:

//this is comment 1
//this is comment 2
//this is comment 3
//this is comment 4

I would like to make it look like:

//this is comment 1

//this is comment 2

//this is comment 3

//this is comment 4

Is there a Vim shortcut to make this transformation on selected lines while staying in command mode?

Answer 1

You can use the :substitute command. With the cursor anywhere on the
first of the lines:

:,+3s/$/\r

This inserts an additional newline at the end of each line.

You can also use the :global command. With the cursor anywhere on
the first of the lines, run:

:,+3g//norm o

For each of the next four lines, this executes the o Normal-mode
command, adding a new blank line.

In both of the commands, the ,+3 prefix is a range for the
command, see :help range. Briefly, the comma separates the addresses
of the starting and ending lines of the range, where the current line
is used if we omit the former of the two addresses. The +3 address
refers to the line that is three lines below from the current line.

Rather than specifying a range, e.g., ,+3, for either of these
commands, you can use the V Normal-mode command to make a Visual
block across all the lines that you want. Then typing : to begin the
command will auto-fill the range specifying the visual block, and you
can then enter either of the two commands starting with s or g:

:'<,'>s/$/\r