Replace n with n+1

Question

I want to replace a number n, with the number n+1. Here's what's working:

:%s/\([0-9]\+\)/\=(submatch(0)+1)/

But this one doesn't work:

:%s/-c \([0-9]\+\)/-c \=(submatch(0)+1)/

Why?

Answer 1

To use \= in substitute it needs to start the replacement string (see :h sub-replace-expression). Also substitue(0) means whole matched string, so also including -c prefix and that will always produce 0 when used in a arithmetic context. To use it correctly only on a number, you should use submatch(1).

And now, to make it work, you need to include -c inside the expression:

s/-c \([0-9]\+\)/\=("-c ".(submatch(1)+1))/

or:

s/\(-c \)\([0-9]\+\)/\=((submatch(1)).(submatch(2)+1))/