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(elisp)Deletion

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Deleting Text
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   Deletion means removing part of the text in a buffer, without saving
it in the kill ring (Note: The Kill Ring).  Deleted text can't be
yanked, but can be reinserted using the undo mechanism (Note: Undo).
Some deletion functions do save text in the kill ring in some special
cases.

   All of the deletion functions operate on the current buffer, and all
return a value of `nil'.

 - Command: erase-buffer
     This function deletes the entire text of the current buffer,
     leaving it empty.  If the buffer is read-only, it signals a
     `buffer-read-only' error; if some of the text in it is read-only,
     it signals a `text-read-only' error.  Otherwise, it deletes the
     text without asking for any confirmation.  It returns `nil'.

     Normally, deleting a large amount of text from a buffer inhibits
     further auto-saving of that buffer "because it has shrunk".
     However, `erase-buffer' does not do this, the idea being that the
     future text is not really related to the former text, and its size
     should not be compared with that of the former text.

 - Command: delete-region start end
     This command deletes the text between positions START and END in
     the current buffer, and returns `nil'.  If point was inside the
     deleted region, its value afterward is START.  Otherwise, point
     relocates with the surrounding text, as markers do.

 - Function: delete-and-extract-region start end
     This function deletes the text between positions START and END in
     the current buffer, and returns a string containing the text just
     deleted.

     If point was inside the deleted region, its value afterward is
     START.  Otherwise, point relocates with the surrounding text, as
     markers do.

 - Command: delete-char count &optional killp
     This command deletes COUNT characters directly after point, or
     before point if COUNT is negative.  If KILLP is non-`nil', then it
     saves the deleted characters in the kill ring.

     In an interactive call, COUNT is the numeric prefix argument, and
     KILLP is the unprocessed prefix argument.  Therefore, if a prefix
     argument is supplied, the text is saved in the kill ring.  If no
     prefix argument is supplied, then one character is deleted, but
     not saved in the kill ring.

     The value returned is always `nil'.

 - Command: delete-backward-char count &optional killp
     This command deletes COUNT characters directly before point, or
     after point if COUNT is negative.  If KILLP is non-`nil', then it
     saves the deleted characters in the kill ring.

     In an interactive call, COUNT is the numeric prefix argument, and
     KILLP is the unprocessed prefix argument.  Therefore, if a prefix
     argument is supplied, the text is saved in the kill ring.  If no
     prefix argument is supplied, then one character is deleted, but
     not saved in the kill ring.

     The value returned is always `nil'.

 - Command: backward-delete-char-untabify count &optional killp
     This command deletes COUNT characters backward, changing tabs into
     spaces.  When the next character to be deleted is a tab, it is
     first replaced with the proper number of spaces to preserve
     alignment and then one of those spaces is deleted instead of the
     tab.  If KILLP is non-`nil', then the command saves the deleted
     characters in the kill ring.

     Conversion of tabs to spaces happens only if COUNT is positive.
     If it is negative, exactly -COUNT characters after point are
     deleted.

     In an interactive call, COUNT is the numeric prefix argument, and
     KILLP is the unprocessed prefix argument.  Therefore, if a prefix
     argument is supplied, the text is saved in the kill ring.  If no
     prefix argument is supplied, then one character is deleted, but
     not saved in the kill ring.

     The value returned is always `nil'.

 - User Option: backward-delete-char-untabify-method
     This option specifies how `backward-delete-char-untabify' should
     deal with whitespace.  Possible values include `untabify', the
     default, meaning convert a tab to many spaces and delete one;
     `hungry', meaning delete all the whitespace characters before point
     with one command, and `nil', meaning do nothing special for
     whitespace characters.