Commands for Fixing Typos
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This chapter describes commands that are especially useful when you catch a mistake in your text just after you have made it, or when you change your mind while composing text on line.

Killing Your Mistakes
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DEL
     Delete last character (delete-backward-char).

M-DEL
     Kill last word (backward-kill-word).

C-x DEL
     Kill to beginning of sentence (backward-kill-sentence).

The DEL character (delete-backward-char) is the most important correction command.  When used among graphic (self-inserting) characters, it can be thought of as canceling the last character typed.

When your mistake is longer than a couple of characters, it might be more convenient to use M-DEL or C-x DEL. M-DEL kills back to the start of the last word, and C-x DEL kills back to the start of the last sentence.  C-x DEL is particularly useful when you are thinking of what to write as you type it, in case you change your mind about phrasing. M-DEL and C-x DEL save the killed text for C-y and M-y to retrieve.  See Yanking.

M-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 DEL except by looking at the screen to see what you did.  It requires less thought to kill the whole word and start over.

Transposing Text
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C-t
     Transpose two characters (transpose-chars).

M-t
     Transpose two words (transpose-words).

C-M-t
     Transpose two balanced expressions (transpose-sexps).

C-x C-t
     Transpose two lines (transpose-lines).

The common error of transposing two adjacent characters can be fixed with the C-t command (transpose-chars).  Normally, C-t transposes the two characters on either side of point.  When given at the end of a line, C-t transposes the last two characters on the line, rather than transposing the last character of the line with the newline, which would be useless.  If you catch a transposition error right away, you can fix it with just C-t. If you catch the error later,  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 (C-r) is often the best way.  See Search.

Meta-t (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, FOO, BAR transposes into BAR, FOO rather than BAR FOO,.

C-M-t (transpose-sexps) is a similar command for transposing two expressions (see Lists), and C-x C-t (transpose-lines) exchanges lines.  It works like M-t but in determines the division of the text into syntactic units differently.

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, C-u 3 C-t moves the character before point forward across three other characters.  This is equivalent to repeating C-t three times.  C-u - 4 M-t moves the word before point backward across four words.  C-u - C-M-t would cancel the effect of plain C-M-t.

A numeric argument of zero transposes the character (word, sexp, line) ending after point with the one ending after the mark (otherwise a command with a repeat count of zero would do nothing).

Case Conversion
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M-- M-l
     Convert last word to lower case.  Note that Meta-- is ``Meta-minus.''

M-- M-u
     Convert last word to all upper case.

M-- M-c
     Convert last word to lower case with capital initial.

A  common error is to type words in the wrong case.  Because of this, the word case-conversion commands M-l, M-u, and M-c do not move the cursor when used with a negative argument. As soon as you see you have mistyped the last word, you can simply case-convert it and continue typing.  See Case.

Checking and Correcting Spelling
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M-$
     Check and correct spelling of word (spell-word).

M-x spell-buffer
     Check and correct spelling of each word in the buffer.

M-x spell-region
     Check and correct spelling of each word in the region.

M-x spell-string
     Check spelling of specified word.

To check the spelling of the word before point, and optionally correct it, use the command M-$ (spell-word).  This command runs an inferior process containing the spell program to see whether the word is correct English.  If it is not, it asks you to edit the word (in the minibuffer) into a corrected spelling, and then performs a query-replace to substitute the corrected spelling for the old one throughout the buffer.

If you exit the minibuffer without altering the original spelling, it means you do not want to do anything to that word.  In that case, the query-replace is not done.

M-x spell-buffer checks each word in the buffer the same way that spell-word does, doing a query-replace for every incorrect word if appropriate.

M-x spell-region is similar to spell-buffer but operates only on the region, not the entire buffer.

M-x spell-string reads a string as an argument and checks whether that is a correctly spelled English word.  It prints a message giving the answer in the echo area.