13.2 Transposing Text

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).