Copy from one register to another
To copy or swap values between registers you can use the :let command, for example to copy the contents of the b register to a:
:let @a=@b
Or copy the contents of the " register to a:
:let @a=@"
Check this Vim Tip for some good key mapping suggestions:
- Comfortable handling of registers
You can do something like this:
let @a = getreg('"')
That'll copy the " register to the a register.