Why when I type * over double slashes '//' doesn't vim highlight it as a search word?

Question

Let's say I have

// that is just a comment
// that is just a comment
// that is just a comment
// that is just a comment
// that is just a comment

And I want to type * at // to use the command cgn and then typing just . instead of classical n . getting this result:

/* that is just a comment
/* that is just a comment
/* that is just a comment
/* that is just a comment
/* that is just a comment

My solutin was setting search register manually:

:let @/='//'

Is there a faster solution? I know visual block changing but my question is just for better understanding of vim.

Answer 1

The reason that this isn't working for you is that forward slash / (ASCII 47), isn't included in your 'iskeyword' setting, which in Vim defaults to @,48-57,_,192-255.¹

You could fix it by adding the forward slash to your 'iskeyword' setting but I wouldn't recommend doing this:

:setlocal iskeyword+=/

The 'iskeyword' setting is used in many places in Vim, and there's a fairly decent chance that by adding forward slash to it you will break things. e.g. Do you like being able to step through the components of a path with the w motion?

Slightly quicker than setting the search register with a :let command is just searching:

/\/\/

If you find the construction of regular expressions to be slow, you could also take advantage of the method the * uses for selecting what to search for:

1. the keyword under the cursor |'iskeyword'|
2. the first keyword after the cursor, in the current line
3. the non-blank word under the cursor
4. [...]

In order that steps 1 & 2 don't find anything, construct a line which contains no keywords, search for it, and then remove it again, by typing:

o//<Esc>*u

You can then carry on with your cgn replacements.

For more details on the 'iskeyword' setting, see :help 'iskeyword' and :help 'isfname' (the latter just for the description of the format of the former), and for more details of how * works see :help *.

_{1: Except on Windows, where it's slightly different: @,48-57,_,128-167,224-235}

Answer 2

You could use ?//<cr> which is quite fast to type. Since n would now work backwards, you'd have to do cgN if you cared about order. Or you could type /<cr> to forward-ize the search.