vimtricks.wiki Concise Vim tricks, one at a time.

How do you change the case of text stored in a register?

Answer

:let @a = toupper(@a)

Explanation

Use Vimscript functions toupper() or tolower() with :let @a = toupper(@a) to convert the case of the entire register contents.

Next

How do you yank a single word into a named register?