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(emacs-lisp-intro.info)Buffer Size & Locations

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Buffer Size and the Location of Point
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   Finally, let's look at several rather simple functions,
`buffer-size', `point', `point-min', and `point-max'.  These give
information about the size of a buffer and the location of point within
it.

   The function `buffer-size' tells you the size of the current buffer;
that is, the function returns a count of the number of characters in
the buffer.

     (buffer-size)

You can evaluate this in the usual way, by positioning the cursor after
the expression and typing `C-x C-e'.

   In Emacs, the current  position of the cursor is called "point".
The expression `(point)' returns a number that tells you where the
cursor is located as a count of the number of characters from the
beginning of the buffer up to point.

   You can see the character count for point in this buffer by
evaluating the following expression in the usual way:

     (point)

As I write this, the value of `point' is 65724.  The `point' function
is frequently used in some of the examples later in this book.

   The value of point depends, of course, on its location within the
buffer.  If you evaluate point in this spot, the number will be larger:

     (point)

For me, the value of point in this location is 66043, which means that
there are 319 characters (including spaces) between the two expressions.

   The function `point-min' is somewhat similar to `point', but it
returns the value of the minimum permissible value of point in the
current buffer.  This is the number 1 unless "narrowing" is in effect.
(Narrowing is a mechanism whereby you can restrict yourself, or a
program, to operations on just a part of a buffer.  Note: Narrowing and
Widening.)  Likewise, the function `point-max'
returns the value of the maximum permissible value of point in the
current buffer.