@c This is part of the Emacs manual.
@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Fixit, Files, Search, Top
@chapter Commands for Fixing Typos
@cindex typos, fixing
@cindex mistakes, correcting

  In this chapter we describe the commands that are especially useful for
the times when you catch a mistake in your text just after you have made
it, or change your mind while composing text on the fly.

  The most fundamental command for correcting erroneous editing is the
undo command, @kbd{C-x u} or @kbd{C-_}.  This command undoes a single
command (usually), a part of a command (in the case of
@code{query-replace}), or several consecutive self-inserting characters.
Consecutive repetitions of @kbd{C-_} or @kbd{C-x u} undo earlier and
earlier changes, back to the limit of the undo information available.
@xref{Undo}, for for more information.

@menu
* Kill Errors:: Commands to kill a batch of recently entered text.
* Transpose::   Exchanging two characters, words, lines, lists...
* Fixing Case:: Correcting case of last word entered.
* Spelling::    Apply spelling checker to a word, or a whole file.
@end menu

@node Kill Errors
@section Killing Your Mistakes

@table @kbd
@item @key{DEL}
Delete last character (@code{delete-backward-char}).
@item M-@key{DEL}
Kill last word (@code{backward-kill-word}).
@item C-x @key{DEL}
Kill to beginning of sentence (@code{backward-kill-sentence}).
@end table

  The @key{DEL} character (@code{delete-backward-char}) is the most
important correction command.  It deletes the character before point.
When @key{DEL} follows a self-inserting character command, you can think
of it as canceling that command.  However, avoid the mistake of thinking
of @key{DEL} as a general way to cancel a command!

  When your mistake is longer than a couple of characters, it might be
more convenient to use @kbd{M-@key{DEL}} or @kbd{C-x @key{DEL}}.
@kbd{M-@key{DEL}} kills back to the start of the last word, and @kbd{C-x
@key{DEL}} kills back to the start of the last sentence.  @kbd{C-x
@key{DEL}} is particularly useful when you change your mind about the
phrasing of the text you are writing.  @kbd{M-@key{DEL}} and @kbd{C-x
@key{DEL}} save the killed text for @kbd{C-y} and @kbd{M-y} to
retrieve.  @xref{Yanking}.@refill

  @kbd{M-@key{DEL}} is often useful even when you have typed only a few
characters wrong, if you know you are confused in your typing and aren't
sure exactly what you typed.  At such a time, you cannot correct with
@key{DEL} except by looking at the screen to see what you did.  Often it
requires less thought to kill the whole word and start again.

@node Transpose
@section Transposing Text

@table @kbd
@item C-t
Transpose two characters (@code{transpose-chars}).
@item M-t
Transpose two words (@code{transpose-words}).
@item C-M-t
Transpose two balanced expressions (@code{transpose-sexps}).
@item C-x C-t
Transpose two lines (@code{transpose-lines}).
@end table

@kindex C-t
@findex transpose-chars
  The common error of transposing two characters can be fixed, when they
are adjacent, with the @kbd{C-t} command (@code{transpose-chars}).  Normally,
@kbd{C-t} transposes the two characters on either side of point.  When
given at the end of a line, rather than transposing the last character of
the line with the newline, which would be useless, @kbd{C-t} transposes the
last two characters on the line.  So, if you catch your transposition error
right away, you can fix it with just a @kbd{C-t}.  If you don't catch it so
fast, you must move the cursor back to between the two transposed
characters.  If you transposed a space with the last character of the word
before it, the word motion commands are a good way of getting there.
Otherwise, a reverse search (@kbd{C-r}) is often the best way.
@xref{Search}.


@kindex C-x C-t
@findex transpose-lines
@kindex M-t
@findex transpose-words
@kindex C-M-t
@findex transpose-sexps
  @kbd{M-t} (@code{transpose-words}) transposes the word before point
with the word after point.  It moves point forward over a word, dragging
the word preceding or containing point forward as well.  The punctuation
characters between the words do not move.  For example, @w{@samp{FOO, BAR}}
transposes into @w{@samp{BAR, FOO}} rather than @samp{@w{BAR FOO,}}.

  @kbd{C-M-t} (@code{transpose-sexps}) is a similar command for transposing
two expressions (@pxref{Lists}), and @kbd{C-x C-t} (@code{transpose-lines})
exchanges lines.  They work like @kbd{M-t} except in determining the
division of the text into syntactic units.

  A numeric argument to a transpose command serves as a repeat count: it
tells the transpose command to move the character (word, sexp, line)
before or containing point across several other characters (words,
sexps, lines).  For example, @kbd{C-u 3 C-t} moves the character before
point forward across three other characters.  It would change
@samp{f@point{}oobar} into @samp{oobf@point{}ar}.  This is equivalent to
repeating @kbd{C-t} three times.  @kbd{C-u - 4 M-t} moves the word
before point backward across four words.  @kbd{C-u - C-M-t} would cancel
the effect of plain @kbd{C-M-t}.@refill

  A numeric argument of zero is assigned a special meaning (because
otherwise a command with a repeat count of zero would do nothing): to
transpose the character (word, sexp, line) ending after point with the
one ending after the mark.

@node Fixing Case
@section Case Conversion

@table @kbd
@item M-- M-l
Convert last word to lower case.  Note @kbd{Meta--} is Meta-minus.
@item M-- M-u
Convert last word to all upper case.
@item M-- M-c
Convert last word to lower case with capital initial.
@end table

@kindex M-@t{-} M-l
@kindex M-@t{-} M-u
@kindex M-@t{-} M-c
  A very common error is to type words in the wrong case.  Because of this,
the word case-conversion commands @kbd{M-l}, @kbd{M-u} and @kbd{M-c} have a
special feature when used with a negative argument: they do not move the
cursor.  As soon as you see you have mistyped the last word, you can simply
case-convert it and go on typing.  @xref{Case}.@refill

@node Spelling
@section Checking and Correcting Spelling
@cindex spelling, checking and correcting
@cindex checking spelling
@cindex correcting spelling

  This section describes the commands to check the spelling of a single
word or of a portion of a buffer.  These commands work with the spelling
checker program Ispell, which is not part of Emacs.
@ifinfo
@xref{Top, Ispell, Overview ispell, ispell.info, The Ispell Manual}.
@end ifinfo

@table @kbd
@item M-x flyspell-mode
Enable Flyspell mode, which highlights all misspelled words.
@item M-$
Check and correct spelling of the word at point (@code{ispell-word}).
@item M-@key{TAB}
Complete the word before point based on the spelling dictionary
(@code{ispell-complete-word}).
@item M-x ispell-buffer
Check and correct spelling of each word in the buffer.
@item M-x ispell-region
Check and correct spelling of each word in the region.
@item M-x ispell-message
Check and correct spelling of each word in a draft mail message, 
excluding cited material.
@item M-x ispell-change-dictionary @key{RET} @var{dict} @key{RET}
Restart the Ispell process, using @var{dict} as the dictionary.
@item M-x ispell-kill-ispell
Kill the Ispell subprocess.
@end table

@cindex Flyspell mode
@findex flyspell-mode
  Flyspell mode is a fully-automatic way to check spelling as you edit
in Emacs.  It operates by checking words as you change or insert them.
When it finds a word that it does not recognize, it highlights that
word.  This does not interfere with your editing, but when you see the
highlighted word, you can move to it and fix it.  Type @kbd{M-x
flyspell-mode} to enable or disable this mode in the current buffer.

  When Flyspell mode highlights a word as misspelled, you can click on
it with @kbd{Mouse-2} to display a menu of possible corrections and
actions.  You can also correct the word by editing it manually in any
way you like.

  The other Emacs spell-checking features check or look up words when
you give an explicit command to do so.  Checking all or part of the
buffer is useful when you have text that was written outside of this
Emacs session and might contain any number of misspellings.

@kindex M-$
@findex ispell-word
  To check the spelling of the word around or next to point, and
optionally correct it as well, use the command @kbd{M-$}
(@code{ispell-word}).  If the word is not correct, the command offers
you various alternatives for what to do about it.

@findex ispell-buffer
@findex ispell-region
  To check the entire current buffer, use @kbd{M-x ispell-buffer}.  Use
@kbd{M-x ispell-region} to check just the current region.  To check
spelling in an email message you are writing, use @kbd{M-x
ispell-message}; that checks the whole buffer, but does not check
material that is indented or appears to be cited from other messages.

  Each time these commands encounter an incorrect word, they ask you
what to do.  They display a list of alternatives, usually including
several ``near-misses''---words that are close to the word being
checked.  Then you must type a character.  Here are the valid responses:

@table @kbd
@item @key{SPC}
Skip this word---continue to consider it incorrect, but don't change it
here.

@item r @var{new} @key{RET}
Replace the word (just this time) with @var{new}.

@item R @var{new} @key{RET}
Replace the word with @var{new}, and do a @code{query-replace} so you
can replace it elsewhere in the buffer if you wish.

@item @var{digit}
Replace the word (just this time) with one of the displayed
near-misses.  Each near-miss is listed with a digit; type that digit to
select it.

@item a
Accept the incorrect word---treat it as correct, but only in this
editing session.

@item A
Accept the incorrect word---treat it as correct, but only in this
editing session and for this buffer.

@item i
Insert this word in your private dictionary file so that Ispell will
consider it correct it from now on, even in future sessions.

@item u
Insert the lower-case version of this word in your private dictionary
file.

@item m
Like @kbd{i}, but you can also specify dictionary completion
information.

@item l @var{word} @key{RET}
Look in the dictionary for words that match @var{word}.  These words
become the new list of ``near-misses''; you can select one of them to
replace with by typing a digit.  You can use @samp{*} in @var{word} as a
wildcard.

@item C-g
Quit interactive spell checking.  You can restart it again afterward
with @kbd{C-u M-$}.

@item X
Same as @kbd{C-g}.

@item x
Quit interactive spell checking and move point back to where it was
when you started spell checking.

@item q
Quit interactive spell checking and kill the Ispell subprocess.

@item C-l
Refresh the screen.

@item C-z
This key has its normal command meaning (suspend Emacs or iconify this
frame).
@end table

@findex ispell-complete-word
  The command @code{ispell-complete-word}, which is bound to the key
@kbd{M-@key{TAB}} in Text mode and related modes, shows a list of
completions based on spelling correction.  Insert the beginning of a
word, and then type @kbd{M-@key{TAB}}; the command displays a completion
list window.  To choose one of the completions listed, click
@kbd{Mouse-2} on it, or move the cursor there in the completions window
and type @key{RET}.  @xref{Text Mode}.

@ignore
@findex reload-ispell
  The first time you use any of the spell checking commands, it starts
an Ispell subprocess.  The first thing the subprocess does is read your
private dictionary, which defaults to the file @file{~/ispell.words}.
Words that you ``insert'' with the @kbd{i} command are added to that
file, but not right away---only at the end of the interactive
replacement procedure.  Use the @kbd{M-x reload-ispell} command to
reload your private dictionary if you edit the file outside of Ispell.
@end ignore

@cindex @code{ispell} program
@findex ispell-kill-ispell
  Once started, the Ispell subprocess continues to run (waiting for
something to do), so that subsequent spell checking commands complete
more quickly.  If you want to get rid of the Ispell process, use
@kbd{M-x ispell-kill-ispell}.  This is not usually necessary, since the
process uses no time except when you do spelling correction.

@vindex ispell-dictionary
  Ispell uses two dictionaries: the standard dictionary and your private
dictionary.  The variable @code{ispell-dictionary} specifies the file
name of the standard dictionary to use.  A value of @code{nil} says to
use the default dictionary.  The command @kbd{M-x
ispell-change-dictionary} sets this variable and then restarts the
Ispell subprocess, so that it will use a different dictionary.