Get list of lines that begin with a pattern

Question

I have two files written in php, both with a bunch of functions. I need to compare these function names with the other file, so I'm trying to get a list of all lines that begin with function. Preferably I would like to have these lines copy to a register. Is there an easy way to do this?

Answer 1

This can be done pretty easily with the global command. I would try this:

:let @a=''
:g/^function/y A

First we must call :let @a='' to make sure that the 'a' register is empty.

Then, the global command is used to apply a command to every line matching a certain regex. In this case, the regex is ^function, and the command is y A (the ex command, not the normal mode command). From :h :y

                            *:y* *:yank* *E850*
:[range]y[ank] [x]  Yank [range] lines [into register x]. Yanking to the
            "* or "+ registers is possible only when the
            |+clipboard| feature is included.

Yanking into uppercase A as opposed to lowercase a means that the yanked text is appended to the register.

Answer 2

You could also use vimgrep. It wouldn't put them in a register but you'd get this list pretty easily.

:vimgrep /^function/ ./*.php
:cw

:cw Opens the quick fix so you can see the result of your search.

See :help :vimgrep and :help quickfix for more info.