The users of international character sets and scripts have established many more-or-less standard coding systems for storing files. These coding systems are typically multibyte, meaning that sequences of two or more bytes are used to represent individual non-ASCII characters.
Internally, Emacs uses its own multibyte character encoding, which is a superset of the Unicode standard. This internal encoding allows characters from almost every known script to be intermixed in a single buffer or string. Emacs translates between the multibyte character encoding and various other coding systems when reading and writing files, and when exchanging data with subprocesses.
The command C-h h (
view-hello-file) displays the file
etc/HELLO, which illustrates various scripts by showing
how to say “hello” in many languages. If some characters can’t be
displayed on your terminal, they appear as ‘?’ or as hollow boxes
(see Undisplayable Characters).
Keyboards, even in the countries where these character sets are
used, generally don’t have keys for all the characters in them. You
can insert characters that your keyboard does not support, using
C-x 8 RET (
insert-char). See Inserting Text.
Shorthands are available for some common characters; for example, you
can insert a left single quotation mark ‘ by typing C-x 8
[, or in Electric Quote mode, usually by simply typing `.
See Quotation Marks. Emacs also supports
various input methods, typically one for each script or
language, which make it easier to type characters in the script.
See Input Methods.
The prefix key C-x RET is used for commands that pertain to multibyte characters, coding systems, and input methods.
The command C-x = (
information about the character at point. In addition to the
character position, which was described in Cursor Position Information, this
command displays how the character is encoded. For instance, it
displays the following line in the echo area for the character
Char: c (99, #o143, #x63) point=28062 of 36168 (78%) column=53
The four values after ‘Char:’ describe the character that follows point, first by showing it and then by giving its character code in decimal, octal and hex. For a non-ASCII multibyte character, these are followed by ‘file’ and the character’s representation, in hex, in the buffer’s coding system, if that coding system encodes the character safely and with a single byte (see Coding Systems). If the character’s encoding is longer than one byte, Emacs shows ‘file ...’.
On rare occasions, Emacs encounters raw bytes: single bytes
whose values are in the range 128 (0200 octal) through 255 (0377
octal), which Emacs cannot interpret as part of a known encoding of
some non-ASCII character. Such raw bytes are treated as if they
belonged to a special character set
eight-bit; Emacs displays
them as escaped octal codes (this can be customized; see Customization of Display). In this case, C-x = shows ‘raw-byte’ instead of
‘file’. In addition, C-x = shows the character codes of
raw bytes as if they were in the range
which is where Emacs maps them to distinguish them from Unicode
characters in the range
With a prefix argument (C-u C-x =), this command additionally
calls the command
describe-char, which displays a detailed
description of the character:
Here’s an example, with some lines folded to fit into this manual:
position: 1 of 1 (0%), column: 0 character: ê (displayed as ê) (codepoint 234, #o352, #xea) preferred charset: unicode (Unicode (ISO10646)) code point in charset: 0xEA script: latin syntax: w which means: word category: .:Base, L:Left-to-right (strong), c:Chinese, j:Japanese, l:Latin, v:Viet to input: type "C-x 8 RET ea" or "C-x 8 RET LATIN SMALL LETTER E WITH CIRCUMFLEX" buffer code: #xC3 #xAA file code: #xC3 #xAA (encoded by coding system utf-8-unix) display: by this font (glyph code) xft:-PfEd-DejaVu Sans Mono-normal-normal- normal-*-15-*-*-*-m-0-iso10646-1 (#xAC) Character code properties: customize what to show name: LATIN SMALL LETTER E WITH CIRCUMFLEX old-name: LATIN SMALL LETTER E CIRCUMFLEX general-category: Ll (Letter, Lowercase) decomposition: (101 770) ('e' '^')