(lemacs.info)Arguments


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Numeric Arguments
=================

   Any Emacs command can be given a "numeric argument".  Some commands
interpret the argument as a repetition count.  For example, giving an
argument of ten to the key `C-f' (the command `forward-char', move
forward one character) moves forward ten characters.  With these
commands, no argument is equivalent to an argument of one.  Negative
arguments are allowed.  Often they tell a command to move or act
backwards.

   If your keyboard has a META key, the easiest way to specify a
numeric argument is to type digits and/or a minus sign while holding
down the the META key.  For example,
     M-5 C-n

moves down five lines.  The characters `Meta-1', `Meta-2', and so on,
as well as `Meta--', do this because they are keys bound to commands
(`digit-argument' and `negative-argument') that are defined to
contribute to an argument for the next command.

   Another way of specifying an argument is to use the `C-u'
(`universal-argument') command followed by the digits of the argument.
With `C-u', you can type the argument digits without holding down shift
keys.  To type a negative argument, start with a minus sign.  Just a
minus sign normally means -1.  `C-u' works on all terminals.

   `C-u' followed by a character which is neither a digit nor a minus
sign has the special meaning of "multiply by four".  It multiplies the
argument for the next command by four.  `C-u' twice multiplies it by
sixteen.  Thus, `C-u C-u C-f' moves forward sixteen characters.  This
is a good way to move forward "fast", since it moves about 1/5 of a line
in the usual size screen.  Other useful combinations are `C-u C-n',
`C-u C-u C-n' (move down a good fraction of a screen), `C-u C-u C-o'
(make "a lot" of blank lines), and `C-u C-k' (kill four lines).

   Some commands care only about whether there is an argument and not
about its value.  For example, the command `M-q' (`fill-paragraph') with
no argument fills text; with an argument, it justifies the text as well.
(Note: Filling, for more information on `M-q'.)  Just `C-u' is a
handy way of providing an argument for such commands.

   Some commands use the value of the argument as a repeat count, but do
something peculiar when there is no argument.  For example, the command
`C-k' (`kill-line') with argument N kills N lines, including their
terminating newlines.  But `C-k' with no argument is special: it kills
the text up to the next newline, or, if point is right at the end of
the line, it kills the newline itself.  Thus, two `C-k' commands with
no arguments can kill a non-blank line, just like `C-k' with an
argument of one.  (Note: Killing, for more information on `C-k'.)

   A few commands treat a plain `C-u' differently from an ordinary
argument.  A few others may treat an argument of just a minus sign
differently from an argument of -1.  These unusual cases will be
described when they come up; they are always to make the individual
command more convenient to use.


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