*pattern.txt*   For Vim version 6.0j.  Last change: 2000 Aug 20


		  VIM REFERENCE MANUAL    by Bram Moolenaar


Patterns and search commands				*pattern-searches*

1. Search commands		|search-commands|
2. The definition of a pattern	|search-pattern|

==============================================================================
1. Search commands					*search-commands*

							*/*
/{pattern}[/]<CR>	Search forward for the [count]'th occurrence of
			{pattern} (exclusive).

/{pattern}/{offset}<CR>	Search forward for the [count]'th occurrence of
			{pattern} and go |{offset}| lines up or down.
			(linewise).

							*/<CR>*
/<CR>			Search forward for the [count]'th latest used
			pattern |last-pattern| with latest used |{offset}|.

//{offset}<CR>		Search forward for the [count]'th latest used
			pattern |last-pattern| with new |{offset}|.  If
			{offset} is empty no offset is used.

							*?*
?{pattern}[?]<CR>	Search backward for the [count]'th previous
			occurrence of {pattern} (exclusive).

?{pattern}?{offset}<CR>	Search backward for the [count]'th previous
			occurrence of {pattern} and go |{offset}| lines up or
			down (linewise).

							*?<CR>*
?<CR>			Search backward for the [count]'th latest used
			pattern |last-pattern| with latest used |{offset}|.

??{offset}<CR>		Search backward for the [count]'th latest used
			pattern |last-pattern| with new |{offset}|.  If
			{offset} is empty no offset is used.

							*n*
n			Repeat the latest "/" or "?" [count] times.
			|last-pattern| {Vi: no count}

							*N*
N			Repeat the latest "/" or "?" [count] times in
			opposite direction. |last-pattern| {Vi: no count}

							*star*
*			Search forward for the [count]'th occurrence of the
			word nearest to the cursor.  The word used for the
			search is the first of:
				1. the keyword under the cursor |'iskeyword'|
				2. the first keyword after the cursor, in the
				   current line
				3. the non-blank word under the cursor
				4. the first non-blank word after the cursor,
				   in the current line
			Only whole keywords are searched for, like with the
			command "/\<keyword\>".  (exclusive)  {not in Vi}

							*#*
#			Same as "*", but search backward.  The pound sign
			(character 163) also works.  If the "#" key works as
			backspace, try using "stty erase <BS>" before starting
			Vim (<BS> is CTRL-H or a real backspace).  {not in Vi}

							*gstar*
g*			Like "*", but don't put "\<" and "\>" around the word.
			This makes the search also find matches that are not a
			whole word.  {not in Vi}

							*g#*
g#			Like "#", but don't put "\<" and "\>" around the word.
			This makes the search also find matches that are not a
			whole word.  {not in Vi}

							*gd*
gd			Goto local Declaration.  When the cursor is on a local
			variable, this command will jump to its declaration.
			First Vim searches for the start of the current
			function, just like "[[".  If it is not found the
			search stops in line 1.  If it is found, Vim goes back
			until a blank line is found.  From this position Vim
			searches for the keyword under the cursor, like with
			"*", but lines that look like a comment are ignored
			(see 'comments' option).
			Note that this is not guaranteed to work, Vim does not
			really check the syntax, it only searches for a match
			with the keyword.  If included files also need to be
			searched use the commands listed in |include-search|.
			{not in Vi}

							*gD*
gD			Goto global Declaration.  When the cursor is on a
			global variable that is defined in the file, this
			command will jump to its declaration.  This works just
			like "gd", except that the search for the keyword
			always starts in line 1.  {not in Vi}

							*CTRL-C*
CTRL-C			Interrupt current (search) command.  Use CTRL-Break on
			MS-DOS |dos-CTRL-Break|.
			In Normal mode, any pending command is aborted.

							*:noh* *:nohlsearch*
:noh[lsearch]		Stop the highlighting for the 'hlsearch' option.  It
			is automatically turned back on when using a search
			command, or setting the 'hlsearch' option.
			This command doesn't work in an autocommand, because
			the highlighting state is saved and restored when
			executing autocommands |autocmd-searchpat|.

While typing the search pattern the current match will be shown if the
'incsearch' option is on.  Remember that you still have to finish the search
command with <CR> to actually position the cursor at the displayed match.  Or
use <Esc> to abandon the search.

All matches for the last used search pattern will be highlighted if you set
the 'hlsearch' option.  This can be suspended with the |:nohlsearch| command.

					*search-offset* *{offset}*
These commands search for the specified pattern.  With "/" and "?" an
additional offset may be given.  There are two types of offsets: line offsets
and character offsets.  {the character offsets are not in Vi}

The offset gives the cursor position relative to the found match:
    [num]	[num] lines downwards, in column 1
    +[num]	[num] lines downwards, in column 1
    -[num]	[num] lines upwards, in column 1
    e[+num]	[num] characters to the right of the end of the match
    e[-num]	[num] characters to the left of the end of the match
    s[+num]	[num] characters to the right of the start of the match
    s[-num]	[num] characters to the left of the start of the match
    b[+num]	[num] characters to the right of the start (begin) of the match
    b[-num]	[num] characters to the left of the start (begin) of the match

If a '-' or '+' is given but [num] is omitted, a count of one will be used.
When including an offset with 'e', the search becomes inclusive (the
character the cursor lands on is included in operations).

Examples:

pattern			cursor position	~
/test/+1		one line below "test", in column 1
/test/e			on the last t of "test"
/test/s+2		on the 's' of "test"
/test/b-3		three characters before "test"

If one of these commands is used after an operator, the characters between
the cursor position before and after the search is affected.  However, if a
line offset is given, the whole lines between the two cursor positions are
affected.

An example of how to search for matches with a pattern and change the match
with another word: >
	/foo<CR>	find "foo"
	c//e		change until end of match
	bar<Esc>	type replacement
	//<CR>		go to start of next match
	c//e		change until end of match
	beep<Esc>	type another replacement
			etc.
<
							*//;*
A very special offset is ';' followed by another search command.  For example: >

   /test 1/;/test
   /test.*/+1;?ing?

The first one first finds the next occurrence of "test 1", and then the first
occurrence of "test" after that.

This is like executing two search commands after each other, except that:
- It can be used as a single motion command after an operator.
- The direction for a following "n" or "N" command comes from the first
  search command.
- When an error occurs the cursor is not moved at all.

							*last-pattern*
The last used pattern and offset are remembered.  They can be used to repeat
the search, possibly in another direction or with another count.  Note that
two patterns are remembered: One for 'normal' search commands and one for the
substitute command ":s".  Each time an empty pattern is given, the previously
used pattern is used.

The 'magic' option sticks with the last used pattern.  If you change 'magic',
this will not change how the last used pattern will be interpreted.
The 'ignorecase' option does not do this.  When 'ignorecase' is changed, it
will result in the pattern to match other text.

All matches for the last used search pattern will be highlighted if you set
the 'hlsearch' option.

To clear the last used search pattern: >
	:let @/ = ""
This will not set the pattern to an empty string, because that would match
everywhere.  The pattern is really cleared, like when starting Vim.

In Vi the ":tag" command sets the last search pattern when the tag is searched
for.  In Vim this is not done, the previous search pattern is still remembered,
unless the 't' flag is present in 'cpoptions'.  The search pattern is always
put in the search history.

If the 'wrapscan' option is on (which is the default), searches wrap around
the end of the buffer.  If 'wrapscan' is not set, the backward search stops
at the beginning and the forward search stops at the end of the buffer.  If
'wrapscan' is set and the pattern was not found the error message "pattern
not found" is given, and the cursor will not be moved.  If 'wrapscan' is not
set the message becomes "search hit BOTTOM without match" when searching
forward, or "search hit TOP without match" when searching backward.  If
wrapscan is set and the search wraps around the end of the file the message
"search hit TOP, continuing at BOTTOM" or "search hit BOTTOM, continuing at
TOP" is given when searching backwards or forwards respectively.  This can be
switched off by setting the 's' flag in the 'shortmess' option.  The highlight
method 'w' is used for this message (default: standout).

							*search-range*
You cannot limit the search command "/" to a certain range of lines.  A trick
to do this anyway is to use the ":substitute" command with the 'c' flag.
Example: >
   :.,300s/Pattern//gc
This command will search from the cursor position until line 300 for
"Pattern".  At the match, you will be asked to type a character.  Type 'q' to
stop at this match, type 'n' to find the next match.

The "*", "#", "g*" and "g#" commands look for a word near the cursor in this
order, the first one that is found is used:
- The keyword currently under the cursor.
- The first keyword to the right of the cursor, in the same line.
- The WORD currently under the cursor.
- The first WORD to the right of the cursor, in the same line.
The keyword may only contain letters and characters in 'iskeyword'.
The WORD may contain any non-blanks (<Tab>s and/or <Space>s).
Note that if you type with ten fingers, the characters are easy to remember:
the "#" is under your left hand middle finger (search to the left and up) and
the "*" is under your right hand middle finger (search to the right and down).

==============================================================================
2. The definition of a pattern		*search-pattern* *pattern* *[pattern]*
					*regular-expression* *regexp* *Pattern*

						*/bar* */\bar* */pattern*
1. A pattern is one or more branches, separated by "\|".  It matches anything
   that matches one of the branches.  Example: "foo\|beep" matches "foo" and
   matches "beep".  If more than one branch matches, the first one is used.

   pattern ::=	    branch
		or  branch \| branch
		or  branch \| branch \| branch
		etc.

						*/branch*
2. A branch is one or more concats, separated by "\&".  It matches the last
   concat, but only if all the preceding contats also match at the same
   position.  Example: "foobeep\&..." matches "foo" in "foobeep".

   branch ::=	    concat
		or  concat \& concat
		or  concat \& concat \& concat
		etc.

						*/concat*
3. A concat is one or more pieces, concatenated.  It matches a match for the
   first piece, followed by a match for the second piece, etc.  Example:
   "f[0-9]b", first matches "f", then a digit and then "b".

   concate  ::=	    piece
		or  piece piece
		or  piece piece piece
		etc.

						*/piece*
4. A piece is an atom, possibly followed by a multi, an indication of how many
   times the atom can be matched.  Example: "a*" matches any sequence of "a"
   characters: "", "a", "aa", etc.  See |/multi|.

   piece   ::=	    atom
		or  atom  multi

						*/atom*
5. An atom can be one of a long list of items.  Each atom matches a certain
   character.  It is often an ordinary character or a character class.  See
   |/ordinary-atom|.  Braces can be used to make a pattern into an atom.  The
   "\z(\)" construct is only for syntax highlighting, see |:syn-ext-match|.

   atom    ::=	    ordinary-atom
   		or  \( pattern \)
		or  \z( pattern \)


Overview of multi items.				*/multi*
More explanation and examples below, follow the links.

	  multi ~
     'magic' 'nomagic'	matches of the preceding atom ~
|/star|	*	\*	0 or more	as many as possible
|/\+|	\+	\+	1 or more	as many as possible (*)
|/\=|	\=	\=	0 or 1		as many as possible (*)

|/\{|	\{n,m}	\{n,m}	n to m		as many as possible (*)
	\{n}	\{n}	n		exactly (*)
	\{n,}	\{n,}	at least n	as many as possible (*)
	\{,m}	\{,m}	0 to m		as many as possible (*)
	\{}	\{}	0 or more	as many as possible (same as *) (*)

|/\{-|	\{-n,m}	\{-n,m}	n to m		as few as possible (*)
	\{-n}	\{-n}	n		exactly (*)
	\{-n,}	\{-n,}	at least n 	as few as possible (*)
	\{-,m}	\{-,m}	0 to m		as few as possible (*)
	\{-}	\{-}	0 or more	as few as possible (*)

|/\@>|	\@>	\@>	1, like matching a whole pattern (*)
|/\@=|	\@=	\@=	nothing, requires a match |/zero-width| (*)
|/\@!|	\@!	\@!	nothing, requires NO match |/zero-width| (*)
|/\@<=|	\@<=	\@<=	nothing, requires a match behind |/zero-width| (*)
|/\@<!|	\@<!	\@<!	nothing, requires NO match behind |/zero-width| (*)

(*) {not in Vi}


Overview of ordinary atoms.				*/ordinary-atom*
More explanation and examples below, follow the links.

      ordinary atom ~
      magic   nomagic	matches ~
|/^|	^	^	start-of-line |/zero-width|
|/\^|	\^	\^	literal '^'
|/$|	$	$	end-of-line |/zero-width|
|/\$|	\$	\$	literal '$'
|/.|	.	\.	any single character (not an end-of-line)
|/\_.|	\_.	\_.	any single character or end-of-line
|/\<|	\<	\<	beginning of a word |/zero-width|
|/\>|	\>	\>	end of a word |/zero-width|
|/\zs|	\zs	\zs	anything, sets start of match
|/\ze|	\ze	\ze	anything, sets end of match

Character classes {not in Vi}:
|/\i|	\i	\i	identifier character (see 'isident' option)
|/\I|	\I	\I	like "\i", but excluding digits
|/\k|	\k	\k	keyword character (see 'iskeyword' option)
|/\K|	\K	\K	like "\k", but excluding digits
|/\f|	\f	\f	file name character (see 'isfname' option)
|/\F|	\F	\F	like "\f", but excluding digits
|/\p|	\p	\p	printable character (see 'isprint' option)
|/\P|	\P	\P	like "\p", but excluding digits
|/\s|	\s	\s	whitespace character: <Space> and <Tab>
|/\S|	\S	\S	non-whitespace character; opposite of \s
|/\d|	\d	\d	digit:				[0-9]
|/\D|	\D	\D	non-digit:			[^0-9]
|/\x|	\x	\x	hex digit:			[0-9A-Fa-f]
|/\X|	\X	\X	non-hex digit:			[^0-9A-Fa-f]
|/\o|	\o	\o	octal digit:			[0-7]
|/\O|	\O	\O	non-octal digit:		[^0-7]
|/\w|	\w	\w	word character:			[0-9A-Za-z_]
|/\W|	\W	\W	non-word character:		[^0-9A-Za-z_]
|/\h|	\h	\h	head of word character:		[A-Za-z_]
|/\H|	\H	\H	non-head of word character:	[^A-Za-z_]
|/\a|	\a	\a	alphabetic character:		[A-Za-z]
|/\A|	\A	\A	non-alphabetic character:	[^A-Za-z]
|/\l|	\l	\l	lowercase character:		[a-z]
|/\L|	\L	\L	non-lowercase character:	[^a-z]
|/\u|	\u	\u	uppercase character:		[A-Z]
|/\U|	\U	\U	non-uppercase character		[^A-Z]
|/\_|	\_x	\_x	where x is any of the characters above: character
			class with end-of-line included
(end of character classes)

|/\e|	\e	\e	<Esc>
|/\t|	\t	\t	<Tab>
|/\r|	\r	\r	<CR>
|/\b|	\b	\b	<BS>
|/\n|	\n	\n	end-of-line
|/~|	~	\~	last given substitute string
|/\1|	\1	\1	same string as matched by first \(\) {not in Vi}
|/\2|	\2	\2	Like "\1", but uses second \(\)
	   ...
|/\9|	\9	\9	Like "\1", but uses ninth \(\)

|/\z|	\z1	\z1	only for syntax highlighting, see |:syn-ext-match|
	   ...
|/\z|	\z9	\z9	only for syntax highlighting, see |:syn-ext-match|

	x	x	a character with no special meaning matches itself

|/[]|	[]	\[]	any character specified inside the []

|/\c|	\c	\c	ignore case
|/\C|	\C	\C	match case
|/\m|	\m	\m	switch 'magic' on for this pattern
|/\M|	\M	\M	switch 'magic' off for this pattern


Example			matches ~
\<\I\i*		or
\<\h\w*
\<[a-zA-Z_][a-zA-Z0-9_]*
			An identifier (e.g., in a C program).

\(\.$\|\. \)		A period followed by <EOL> or a space.

[.!?][])"']*\($\|[ ]\)	A search pattern that finds the end of a sentence,
			with almost the same definition as the ")" command.


Magic							*/magic*

Patterns may contain special characters, depending on the setting of the
'magic' option.  See the lists below.
							*/\m* */\M*
Use of "\m" makes the pattern after it be interpreted as if 'magic' is set,
ignoring the actual value of the 'magic' option.
Use of "\M" makes the pattern after it be interpreted as if 'nomagic' is used.
{only Vim supports \m and \M}

It is recommended to always keep the 'magic' option at the default setting,
which is 'magic'.  This avoids portability problems.  To make a pattern immune
to the 'magic' option being set or not, put "\m" or "\M" at the start of the
pattern.


Multi items

An atom can be followed by an indication of how many times the atom can be
matched and in what way.  This is called a multi.  See |/multi| for an
overview.

It is not possible to use a multi that can match more than one time after an
atom that can match an empty string.  That's because this could result in an
endless loop.  If you try it, you will get this error message: >
 	*, \+ or \{ operand could be empty
<
							*/star* */\star*
*	(use \* with 'nomagic')
	Matches 0 or more of the preceding atom, as many as possible.
	Example  'nomagic'	matches ~
	a*	   a\*		"", "a", "aa", "aaa", etc.
	.*	   \.\*		anything, also an empty string, no end-of-line
	\_.*	   \_.\*	everything up to the end of the buffer
	\_.*END	   \_.\*END	everything up to and including the last "END"
				in the buffer

	Be aware that repeating "\_." can match a lot of text and take a long
	time.  For example, "\_.*END" matches all text from the current
	position to the last occurrence of "END" in the file.  Since the "*"
	will match as many as possible, this first skips over all lines until
	the end of the file and then tries matching "END", backing up one
	character at a time.

							*/\+*
\+	Matches 1 or more of the preceding atom, as many as possible. {not in
	Vi}
	Example		matches ~
	^.\+$		any non-empty line
	\s\+		white space of at least one character

							*/\=*
\=	Matches 0 or 1 of the preceding atom, as many as possible. {not in Vi}
	Example		matches ~
	foo\=		"fo" and "foo"

							*/\{*
\{n,m}	Matches n to m of the preceding atom, as many as possible
\{n}	Matches n of the preceding atom
\{n,}	Matches at least n of the preceding atom, as many as possible
\{,m}	Matches 0 to m of the preceding atom, as many as possible
\{}	Matches 0 or more of the preceding atom, as many as possible (like *)
							*/\{-*
\{-n,m}	matches n to m of the preceding atom, as few as possible
\{-n}	matches n of the preceding atom
\{-n,}	matches at least n of the preceding atom, as few as possible
\{-,m}	matches 0 to m of the preceding atom, as few as possible
\{-}	matches 0 or more of the preceding atom, as few as possible
	{Vi does not have any of these}

	n and m are positive decimal numbers

	If a "-" appears immediately after the "{", then a shortest match
	first algorithm is used (see example below).  In particular, "\{-}" is
	the same as "*" but uses the shortest match first algorithm.  BUT: A
	match that starts earlier is preferred over a shorter match: "a\{-}b"
	matches "aaab" in "xaaab".

	Example			matches ~
	ab\{2,3}c		"abbc" or "abbbc"
	a\{5}			"aaaaa".
	ab\{2,}c		"abbc", "abbbc", "abbbbc", etc
	ab\{,3}c		"ac", "abc", "abbc" or "abbbc".
	a[bc]\{3}d		"abbbd", "abbcd", "acbcd", "acccd", etc.
	a\(bc\)\{1,2}d		"abcd" or "abcbcd"
	a[bc]\{-}[cd]		"abc" in "abcd"
	a[bc]*[cd]		"abcd" in "abcd"

							*/\@=*
\@=	Matches the preceding atom with zero width. {not in Vi}
	Like '(?=pattern)" in Perl.
	Example			matches ~
	foo\(bar\)\@=		"foo" in "foobar"
	foo\(bar\)\@=foo	nothing
							*/zero-width*
	When using "\@=" (or "^", "$", "\<", "\>") no characters are included
	in the match.  These items are only used to check if a match can be
	made.  This can be tricky, because a match with following items will
	be done in the same position.  The last example above will not match
	"foobarfoo", because it tries match "foo" in the same position where
	"bar" matched.

	Note that using "\&" works exactly the same as using "\@=": "foo\&.."
	is the same as "\(foo\)\@=..".  But using "\&" is easier.


							*/\@!*
\@!	Matches with zero width if the preceding atom does NOT match at the
	current position |/zero-width| {not in Vi}
	Like '(?!pattern)" in Perl.
	Example			matches ~
	foo\(bar\)\@!		any "foo" not followed by "bar"
	a.\{-}p\@!		"a", "ap", "app", etc. not followed by a "p"

	Using "\@!" is tricky, because there are many places where a pattern
	does not match.  "a.*p\@!" will match from an "a" to the end of the
	line, because ".*" can match all characters in the line and the "p"
	doesn't match at the end of the line.  "a.\{-}p\@!" will match any
	"a", "ap", "aap", etc. that isn't followed by a "p", because the "."
	can match a "p" and "p\@!" doesn't match after that.

	You can't use "\@!" to look for a non-match before the matching
	position: "\(foo\)\@!bar" will match "bar" in "foobar", because at the
	position where "bar" matches, "foo" does not match.  To avoid matching
	"foobar" you could use "\(foo\)\@!...bar", but that doesn't match a
	bar at the start of a line. Use "\(foo\)\@<!bar".

							*/\@<=*
\@<=	Matches with zero width if the preceding atom matches just before what
	follows. |/zero-width| {not in Vi}
	Like '(?>=pattern)" in Perl, but Vim allows non-fixed-width patterns.
	Example			matches ~
	\(an\_\s\+\)\@<=file	"file" after "an" and white space or a
				end-of-line

	"\@<=" and "\@<!" check for matches just before what follows.
	Theoretically these matches could start anywhere before this position.
	But to limit the time needed only the line where what follows matches
	is searched, and one line before that (if there is one).  This should
	be sufficient to match most things and not be too slow.

							*/\@<!*
\@<!	Matches with zero width if the preceding atom does NOT match just
	before what follows. |/zero-width| {not in Vi}
	Like '(?>!pattern)" in Perl, but Vim allows non-fixed-width patterns.
	Example			matches ~
	\(foo\)\@<!bar		any "bar" that's not in "foobar"

							*/\@>*
\@>	Matches the preceding atom like matching a whole pattern. {not in Vi}
	Like '(?>pattern)" in Perl.
	Example		matches ~
	\(.\{-}{{{\)\@>
	\(a*\)\@>a	nothing (the "a*" takes all the "a"'s, there can't be
			another one following)

	This matches the preceding atom as if it was a pattern by itself.  If
	it doesn't match, there is no retry with shorter sub-matches or
	anything.  Observe this difference: "a*b" and "a*ab" both match
	"aaab", but in the first case the "a*" matches only the first two
	"a"s.  "\(a*\)\@>ab" will not match "aaab", because the "a*" matches
	the "aaa" (as many "a"s as possible), thus the "ab" can't match.


An ordinary atom can be:

							*/^*
^	At beginning of pattern or after "\|", "\(", or "\n": matches start of
	line; at other positions, matches literal '^'. |/zero-width|
	Example		matches ~
	^beep(		Probably the start of the C function "beep".

							*/\^*
\^	At any position, matches literal '^'.

							*/$*
$	At end of pattern or in front of "\|" or "\)", matches end-of-line
	<EOL>; at other positions, matches literal '$'. |/zero-width|

							*/\$*
\$	At any position, matches literal '$'.

.	(with 'nomagic': \.)				*/.* */\.*
	Matches any single character, but not an end-of-line.

							*/\_.*
\_.	Matches any single character or end-of-line.
	Careful: "\_.*" matches all text to the end of the buffer!

							*/\<*
\<	Matches the beginning of a word: The next char is the first char of a
	word. |/zero-width|

							*/\>*
\>	Matches the end of a word: The previous char is the last char of a
	word. |/zero-width|

							*/\zs*
\zs	Matches at any position, and sets the start of the match there: The
	next char is the first char of the whole match. |/zero-width|
	Can be used multiple times, the last one encountered in a matching
	branch is used.
	Example: "^\s*\zsif" matches an "if" at the start of a line, ignoring
	white space.
							*/\ze*
\ze	Matches at any position, and sets the end of the match there: The
	previous char is the last char of the whole match. |/zero-width|
	Can be used multiple times, the last one encountered in a matching
	branch is used.
	Example: "end\ze\(if\|for\)" matches the "end" in "endif" and
	"endfor".

Character classes: {not in Vi}
\i	identifier character (see 'isident' option)	*/\i*
\I	like "\i", but excluding digits			*/\I*
\k	keyword character (see 'iskeyword' option)	*/\k*
\K	like "\k", but excluding digits			*/\K*
\f	file name character (see 'isfname' option)	*/\f*
\F	like "\f", but excluding digits			*/\F*
\p	printable character (see 'isprint' option)	*/\p*
\P	like "\p", but excluding digits			*/\P*

						*whitespace* *white-space*
\s	whitespace character: <Space> and <Tab>		*/\s*
\S	non-whitespace character; opposite of \s	*/\S*
\d	digit:				[0-9]		*/\d*
\D	non-digit:			[^0-9]		*/\D*
\x	hex digit:			[0-9A-Fa-f]	*/\x*
\X	non-hex digit:			[^0-9A-Fa-f]	*/\X*
\o	octal digit:			[0-7]		*/\o*
\O	non-octal digit:		[^0-7]		*/\O*
\w	word character:			[0-9A-Za-z_]	*/\w*
\W	non-word character:		[^0-9A-Za-z_]	*/\W*
\h	head of word character:		[A-Za-z_]	*/\h*
\H	non-head of word character:	[^A-Za-z_]	*/\H*
\a	alphabetic character:		[A-Za-z]	*/\a*
\A	non-alphabetic character:	[^A-Za-z]	*/\A*
\l	lowercase character:		[a-z]		*/\l*
\L	non-lowercase character:	[^a-z]		*/\L*
\u	uppercase character:		[A-Z]		*/\u*
\U	non-uppercase character		[^A-Z]		*/\U*

	NOTE: Using the atom is faster than the [] form.

	NOTE: 'ignorecase', "\c" and "\C" are not used by character classes.

							*/\_*
\_x	Where "x" is any of the characters above: The character class with
	end-of-line added
(end of character classes)

\e	matches <Esc>					*/\e*
\t	matches <Tab>					*/\t*
\r	matches <CR>					*/\r*
\b	matches <BS>					*/\b*
\n	matches a end-of-line				*/\n*

~	matches the last given substitute string    */~* */\~*

\(\)	A pattern enclosed by escaped parentheses      */\(\)*
		(e.g., "\(^a\)") matches that pattern		*/\)*

\1      Matches the same string that was matched by	*/\1*
		the first sub-expression in \( and \). {not in Vi}
		Example: "\([a-z]\).\1" matches "ata", "ehe", "tot",
		etc.
\2      Like "\1", but uses second sub-expression,	*/\2*
   ...							*/\3*
\9      Like "\1", but uses ninth sub-expression.	*/\9*
	Note: The numbering of groups is done based on which "\(" comes first
	(going left to right).

x	A single character, with no special meaning, matches itself

							*/\* */\\*
\x	A backslash followed by a single character, with no special meaning,
	is reserved for future expansions

[]	(with 'nomagic': \[])		*/[]* */\[]* */\_[]* */collection*
\_[]
	A collection. This is a sequence of characters enclosed in brackets.
	It matches any single character in the collection.
	Example		matches ~
	[xyz]		any 'x', 'y' or 'z'
	[a-zA-Z]$	any alphabetic character at the end of a line
	\c[a-z]$	same

	With "\_" prepended the collection also includes the end-of-line.
	The same can be done by including "\n" in the collection.  The
	end-of-line is also matched when the collection starts with "^"!  Thus
	"\_[^ab]" matches the end-of-line and any character but "a" and "b".
	This makes it Vi compatible: Without the "\_" or "\n" the collection
	does not match an end-of-line.

	If the sequence begins with "^", it matches any single character NOT
	in the collection: "[^xyz]" matches anything but 'x', 'y' and 'z'.
	- If two characters in the sequence are separated by '-', this is
	  shorthand for the full list of ASCII characters between them.  E.g.,
	  "[0-9]" matches any decimal digit.
	- A character class expression is evaluated to the set of characters
	  belonging to that character class.  The following character classes
	  are supported:
			  Name		Contents ~
*[:alnum:]*		  [:alnum:]     letters and digits
*[:alpha:]*		  [:alpha:]     letters
*[:blank:]*		  [:blank:]     space and tab characters
*[:cntrl:]*		  [:cntrl:]     control characters
*[:digit:]*		  [:digit:]     decimal digits
*[:graph:]*		  [:graph:]     printable characters excluding space
*[:lower:]*		  [:lower:]     lowercase letters (all letters when
					'ignorecase' is used)
*[:print:]*		  [:print:]     printable characters including space
*[:punct:]*		  [:punct:]     punctuation characters
*[:space:]*		  [:space:]     whitespace characters
*[:upper:]*		  [:upper:]     uppercase letters (all letters when
					'ignorecase' is used)
*[:xdigit:]*		  [:xdigit:]    hexadecimal digits
*[:return:]*		  [:return:]	the <CR> character
*[:tab:]*		  [:tab:]	the <Tab> character
*[:escape:]*		  [:escape:]	the <Esc> character
*[:backspace:]*		  [:backspace:]	the <BS> character
	  The brackets in character class expressions are additional to the
	  brackets delimiting a collection.  For example, the following is a
	  plausible pattern for a UNIX filename: "[-./[:alnum:]_~]\+" That is,
	  a list of at least one character, each of which is either '-', '.',
	  '/', alphabetic, numeric, '_' or '~'.
							  */\]*
	- To include a literal ']', '^', '-' or '\' in the collection, put a
	  backslash before it: "[xyz\]]", "[\^xyz]", "[xy\-z]" and "[xyz\\]".
	  (Note: POSIX does not support the use of a backslash this way).  For
	  ']' you can also make it the first character (following a possible
	  "^"):  "[]xyz]" or "[^]xyz]" {not in Vi}.
	  For '-' you can also make it the first or last character: "[-xyz]",
	  "[^-xyz]" or "[xyz-]".  For '\' you can also let it be followed by
	  any character that's not in "^]-\bertn".  "[\xyz]" matches '\', 'x',
	  'y' and 'z'.  It's better to use "\\" though, future expansions may
	  use other characters after '\'.
	- The following translations are accepted when the 'l' flag is not
	  included in 'cpoptions' {not in Vi}:
		\e	<Esc>
		\t	<Tab>
		\r	<CR>	(NOT end-of-line!)
		\b	<BS>
	  NOTE: The other backslash codes mentioned above do not work inside
	  []!
	- Matching with a collection can be slow, because each character in
	  the text has to be compared with each character in the collection.
	  Use one of the other atoms above when possible.  Example: "\d" is
	  much faster than "[0-9]" and matches the same characters.


Ignoring case in a pattern					*/ignorecase*

If the 'ignorecase' option is on, the case of normal letters is ignored.
'smartcase' can be set to ignore case when the pattern contains uppercase
letters only.
							*/\c* */\C*
When "\c" appears anywhere in the pattern, the whole pattern is handled like
'ignorecase' is on.  The actual value of 'ignorecase' and 'smartcase' is
ignored.  "\C" does the opposite: Force matching case for the whole pattern.
{only Vim supports \c and \C}
Note that 'ignorecase', "\c" and "\C" are not used for the character classes.

Examples:
      pattern	'ignorecase'  'smartcase'	matches ~
	foo	  off	       on or off	foo
	foo	  on	       on or off	foo Foo FOO
	Foo	  on	       off		foo Foo FOO
	Foo	  on	       on		    Foo		
	\cfoo	  on or off    on or off	foo Foo FOO
	foo\C	  on or off    on or off	foo


Technical detail:				*NL-used-for-Nul*
<Nul> characters in the file are stored as <NL> in memory.  In the display
they are shown as "^@".  The translation is done when reading and writing
files.  To match a <Nul> with a search pattern you can just enter CTRL-@ or
"CTRL-V 000".  This is probably just what you expect.  Internally the
character is replaced with a <NL> in the search pattern.  What is unusual is
that typing CTRL-V CTRL-J also inserts a <NL>, thus also searches for a <Nul>
in the file.  {Vi cannot handle <Nul> characters in the file at all}

						*CR-used-for-NL*
When 'fileformat' is "mac", <NL> characters in the file are stored as <CR>
characters internally.  In the display they are shown as "^M".  Otherwise this
works similar to the usage of <NL> for a <Nul>.

When working with expression evaluation, a <NL> character in the pattern
matches a <NL> in the string.  The use of "\n" (backslash n) to match a <NL>
doesn't work there, it only works to match text in the buffer.

 vim:tw=78:
