Visual block. Some right-end selections seem impossible

Question

I want to use visual block mode (ctl-v) to select all the comments but none of the code:

a = 1             // short comment
b = 2             // this one is a longer comment
c = 3             // shortest

My selection is marked with X characters here. Notice that if I start at the top-left my selection is unsatisfactory:

a = 1             XXXXXXXXXXXXXXXX
b = 2             XXXXXXXXXXXXXXXX longer comment
c = 3             XXXXXXXXXXX

If I start middle-left I lose either the first or third line:

a = 1             // short comment
b = 2             XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
c = 3             XXXXXXXXXXX

And so on. I'm missing something here. What is the secret? I've tried :help and searched here and Google.

Answer 1

The secret is to press $ after you have expanded your block vertically:

<C-v>jj$

or to press $ before expanding your block vertically:

<C-v>$jj

Well, $ is the secret.

^{…which is not that surprising, after all.}

Answer 2

One (*) secret is:

set virtualedit=block

... in your vimrc :)

(:h virtualedit will explain everything).

A disadvantage of this method: when yanking, you get trailing spaces on the shorter lines.

(*) The other is in the answer provided by @romainl.

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BTW, for the secret of the golden rivet, see this instead.