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Digraphs                                        digraph digraphs Digraphs

Digraphs are used to enter characters that normally cannot be entered by
an ordinary keyboard.  These are mostly printable non-ASCII characters.  The
digraphs are easier to remember than the decimal number that can be entered
with CTRL-V (see i_CTRL-V).

There is a brief introduction on digraphs in the user manual: 24.9
An alternative is using the 'keymap' option.

1. Defining digraphs    digraphs-define
2. Using digraphs       digraphs-use
3. Default digraphs     digraphs-default

{Vi does not have any of these commands}

==============================================================================
1. Defining digraphs                                    digraphs-define

                                                :dig :digraphs
:dig[raphs]             show currently defined digraphs.
                                                        E104 E39
:dig[raphs] {char1}{char2} {number} ...
                        Add digraph {char1}{char2} to the list.  {number} is
                        the decimal representation of the character.  Normally
                        it is the Unicode character, see digraph-encoding.
                        Example: >
        :digr e: 235 a: 228
<                       Avoid defining a digraph with '_' (underscore) as the
                        first character, it has a special meaning in the
                        future.

Vim is normally compiled with the +digraphs feature.  If the feature is
disabled, the ":digraph" command will display an error message.

Example of the output of ":digraphs": >
 TH Þ  222  ss ß  223  a! à  224  a' á  225  a> â  226  a? ã  227  a: ä  228

The first two characters in each column are the characters you have to type to
enter the digraph.

In the middle of each column is the resulting character.  This may be mangled
if you look at it on a system that does not support digraphs or if you print
this file.

                                                        digraph-encoding
The decimal number normally is the Unicode number of the character.  Note that
the meaning doesn't change when 'encoding' changes.  The character will be
converted from Unicode to 'encoding' when needed.  This does require the
conversion to be available, it might fail.  For the NUL character you will see
"10".  That's because NUL characters are internally represented with a NL
character.  When you write the file it will become a NUL character.
        
When Vim was compiled without the +multi_byte feature, you need to specify
the character in the encoding given with 'encoding'.  You might want to use
something like this: >

        if has("multi_byte")
                digraph oe 339
        elseif &encoding == "iso-8859-15"
                digraph oe 189
        endif

This defines the "oe" digraph for a character that is number 339 in Unicode
and 189 in latin9 (iso-8859-15).

==============================================================================
2. Using digraphs                                       digraphs-use

There are two methods to enter digraphs:                        i_digraph
        CTRL-K {char1} {char2}          or
        {char1} <BS> {char2}
The first is always available; the second only when the 'digraph' option is
set.

If a digraph with {char1}{char2} does not exist, Vim searches for a digraph
{char2}{char1}.  This helps when you don't remember which character comes
first.

Note that when you enter CTRL-K {char1}, where {char1} is a special key, Vim
enters the code for that special key.  This is not a digraph.

Once you have entered the digraph, Vim treats the character like a normal
character that occupies only one character in the file and on the screen.
Example: >
        'B' <BS> 'B'    will enter the broken '|' character (166)
        'a' <BS> '>'    will enter an 'a' with a circumflex (226)
        CTRL-K '-' '-'  will enter a soft hyphen (173)

The current digraphs are listed with the ":digraphs" command.  Some of the
default ones are listed below digraph-table.

For CTRL-K, there is one general digraph: CTRL-K <Space> {char} will enter
{char} with the highest bit set.  You can use this to enter meta-characters.

The <Esc> character cannot be part of a digraph.  When hitting <Esc>, Vim
stops digraph entry and ends Insert mode or Command-line mode, just like
hitting an <Esc> out of digraph context.  Use CTRL-V 155 to enter meta-ESC
(CSI).

If you accidentally typed an 'a' that should be an 'e', you will type 'a' <BS>
'e'.  But that is a digraph, so you will not get what you want.  To correct
this, you will have to type <BS> e again.  To avoid this don't set the
'digraph' option and use CTRL-K to enter digraphs.

You may have problems using Vim with characters which have a value above 128.
For example: You insert ue (u-umlaut) and the editor echoes \334 in Insert
mode.  After leaving the Insert mode everything is fine.  Note that fmt
removes all characters with a value above 128 from the text being formatted.
On some Unix systems this means you have to define the environment-variable
LC_CTYPE.  If you are using csh, then put the following line in your .cshrc: >
        setenv LC_CTYPE iso_8859_1

==============================================================================
3. Default digraphs                                     digraphs-default

Vim comes with a set of default digraphs.  Check the output of ":digraphs" to
see them.

On most systems Vim uses the same digraphs.  They work for the Unicode and
ISO-8859-1 character sets.  These default digraphs are taken from the RFC1345
mnemonics.  To make it easy to remember the mnemonic, the second character has
a standard meaning:

        char name               char    meaning
        Exclamation mark        !       Grave
        Apostrophe              '       Acute accent
        Greater-Than sign       >       Circumflex accent
        Question mark           ?       Tilde
        Hyphen-Minus            -       Macron
        Left parenthesis        (       Breve
        Full stop               .       Dot above
        Colon                   :       Diaeresis
        Comma                   ,       Cedilla
        Underline               _       Underline
        Solidus                 /       Stroke
        Quotation mark          "       Double acute accent
        Semicolon               ;       Ogonek
        Less-Than sign          <       Caron
        Zero                    0       Ring above
        Two                     2       Hook
        Nine                    9       Horn

        Equals                  =       Cyrillic
        Asterisk                *       Greek
        Percent sign            %       Greek/Cyrillic special
        Plus                    +       smalls: Arabic, capitals: Hebrew
        Three                   3       some Latin/Greek/Cyrillic letters
        Four                    4       Bopomofo
        Five                    5       Hiragana
        Six                     6       Katakana

Example: a: is ä  and o: is ö

These are the RFC1345 digraphs for the one-byte characters.  See the output of
":digraphs" for the others.  The characters above 255 are only available when
Vim was compiled with the +multi_byte feature.