C-u as a prefix to many key presses in emacs and conkeror before. I never really knew what it did. Recently, I read this that show you how to repeat commands by typing
# is a number such as 5 or 100, before a command, such as
0. I’ve also read function definitions in different
.el files or emacs’ documentation that speaks of function arguments. I knew that emacs commands correspond to functions, but I never knew how to pass in arguments.
C-u # and
# with a number) passes numeric arguments to the function called.
# is equivalent to
M-4. Read this for a more thorough explanation. This shows how one can “overload” a function using the prefix argument.