search and replace block to a line

Question

I would like to replace a multiline block to one line

for example :

    if (... ){
     //comment0
     line1
     line2
   }
   some code
   if (... ){
     //comment0
     line1
     line2
   }

into:

if_function()
some code
if_function()

is there a fast way to do this? I tried to yank the block into register

 shift+V
 4j
 "fy

and then replace, but I don't know how to reference the register tried:

%s/@f/if_function/g

and

%s/\@f/if_function/g

and

%s/"f/if_function/g

and

%s/\"f/if_function/g

but they all doesn't work

Answer 1

found how to paste register ctrl+r

so I enter to visual mode, and marked the block

shift+ v
4j

and used the replace command:

:%s/^Rf/if_function/g

Answer 2

How I would probably approach this:

1. Navigate: possibly something like /if then $; the goal is to be on the curly brace for the % key. Or you could just get inside the curlies for a{
2. Change: cV% or cVa{ and type if_function()
3. Change populates a register. If I had more of the same edit, I would first navigate again (maybe n?) and then . to repeat. When I’m done, paste the original content somewhere with p if I were, for example, extracting a function. (Actually, I might have yanked it, pasted it, and created the function before starting all the changes, but since c does fill a register we can do things in this order, which almost seems like what you’re looking for.)