The common error of transposing two characters can be fixed, when they
are adjacent, with the C-t command (
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, 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 C-t. If you don't catch it so
fast, you must move the cursor back between the two transposed
characters before you type C-t. If you transposed a space with
the last character of the word before it, the word motion commands
(M-f, M-b, etc.) are a good way of getting there.
Otherwise, a reverse search (C-r) is often the best way.
M-t transposes the word before point with the word after point
transpose-words). 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,’. When point is at the end of the line, it will
transpose the word before point with the first word on the next line.
transpose-sexps) is a similar command for
transposing two expressions (see Expressions), and C-x C-t
transpose-lines) exchanges lines. They work like M-t
except as regards the units of text they transpose.
A numeric argument to a transpose command serves as a repeat count: it tells the transpose command to move the character (or word or expression or line) before or containing point across several other characters (or words or expressions or lines). For example, C-u 3 C-t moves the character before point forward across three other characters. It would change ‘f-!-oobar’ into ‘oobf-!-ar’. 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 is assigned a special meaning (because otherwise a command with a repeat count of zero would do nothing): to transpose the character (or word or expression or line) ending after point with the one ending after the mark.