How do I access and manipulate the last search pattern as a register?

Explanation

Vim stores the last search pattern in the special / register. Like any named register, you can read it, paste it, and even write to it — which silently sets the current search highlight without adding to the search history.

How it works

• "/p — paste the last search pattern as text
• <C-r>/ — insert the last search pattern in command-line or insert mode
• :let @/ = "pattern" — set the search register (highlights pattern without a / search)
• :let @/ = @a — use the contents of register a as the search pattern
• :let @/ = "" — clear the search highlight programmatically (equivalent to :nohlsearch but persistent)

Example

You searched for \v(foo|bar) and now want to use it in a substitution on a different range:

:let @/
" Shows: '\v(foo|bar)'
:1,10s//replacement/g
" Reuses the last search pattern for the range 1-10

Or copy a word into the search register to highlight it without navigating away:

:let @/ = expand('<cword>')

Tips

• Writing to @/ triggers hlsearch highlighting immediately without moving the cursor
• This is useful in Vimscript functions to set up a highlight without side-effects
• The / register is read-only when accessed via <C-r>/ but fully writable via :let @/ = ...
• Combine with set hlsearch for instant visual feedback on programmatic searches