*eval.txt*      For Vim version 5.2j.  Last modification: 1998 Aug 07


		  VIM REFERENCE MANUAL    by Bram Moolenaar


Expression evaluation					*expression* *expr*

Note: Expression evaluation can be disabled at compile time.  If this has been
done, the features in this document are not available.  See |+eval|.

1. Variables		|variables|
2. Expression syntax	|expression-syntax|
3. Internal variable	|internal-variables|
4. Builtin Functions	|functions|
5. Defining functions	|user-functions|
6. Commands		|expression-commands|

{Vi does not have any of these commands}

==============================================================================
1. Variables						*variables*

There are two types of variables:

Number		a 32 bit signed number
String		a NUL terminated string of 8-bit unsigned characters.

These are converted automatically, depending on how they are used.

Conversion from a Number to a String is by making the ASCII representation of
the Number.  Examples:
>	Number 123	-->	String "123"
>	Number 0	-->	String "0"
>	Number -1	-->	String "-1"

Conversion from a String to a Number is done by converting the first digits
to a number.  Hexadecimal "0xf9" and Octal "017" numbers are recognized.  If
the String doesn't start with digits, the result is zero.  Examples:
>	String "456"	-->	Number 456
>	String "6bar"	-->	Number 6
>	String "foo"	-->	Number 0
>	String "0xf1"	-->	Number 241
>	String "0100"	-->	Number 64

For boolean operators Numbers are used.  Zero is FALSE, non-zero is TRUE.

Note that in the command
	:if "foo"
"foo" is converted to 0, which means FALSE.  To test for a non-empty string,
use strlen():
	:if strlen("foo")

==============================================================================
2. Expression syntax					*expression-syntax*

Expression syntax summary, from least to most significant:

|expr1|	expr2 || expr2 ..	logical OR

|expr2|	expr3 && expr3 ..	logical AND

|expr3|	expr4 == expr4		equal
	expr4 != expr4		not equal
	expr4 >	 expr4		greater than
	expr4 >= expr4		greater than or equal
	expr4 <	 expr4		smaller than
	expr4 <= expr4		smaller than or equal
	expr4 =~ expr4		regexp matches
	expr4 !~ expr4		regexp doesn't match

|expr4|	expr5 +	 expr5 ..	number addition
	expr5 -	 expr5 ..	number subtraction
	expr5 .	 expr5 ..	string concatenation

|expr5|	expr6 *	 expr6 ..	number multiplication
	expr6 /	 expr6 ..	number division
	expr6 %	 expr6 ..	number modulo

|expr6|	! expr6			logical NOT
	- expr6			unary minus

|expr7|	expr8[expr1]		index in String

|expr8|	number			number constant
	"string"		string constant
	'string'		literal string constant
	&option			option value
	(expr1)			nested expression
	variable		internal variable
	$VAR			environment variable
	@r			contents of register 'r'
	function(expr1, ...)	function call

".." indicates that the operations in this level can be concatenated.
Example:
>	&nu || &list && &shell == "csh"

All expressions within one level are parsed from left to right.


expr1 and expr2						*expr1* *expr2*
---------------

						*expr-barbar* *expr-&&*
The "||" and "&&" operators take one argument on each side.  The arguments
are (converted to) Numbers.  The result is:

         input				 output		    ~
    n1		n2		n1 || n2	n1 && n2    ~
    zero	zero		zero		zero
    zero	non-zero	non-zero	zero
    non-zero	zero		non-zero	zero
    non-zero	non-zero	non-zero	non-zero

The operators can be concatenated, for example:

>	&nu || &list && &shell == "csh"

Note that "&&" takes precedence over "||", so this has the meaning of:

>	&nu || (&list && &shell == "csh")

All arguments are computed, there is no skipping if the value of an argument
doesn't matter, because the result is already known.  This is different from
C, although it only matters for errors (unknown variables), since there are no
side effects from an expression.


expr3							*expr3*
-----
	expr4 == expr4		equal			*expr-==*
	expr4 != expr4		not equal		*expr-!=*
	expr4 >	 expr4		greater than		*expr->*
	expr4 >= expr4		greater than or equal	*expr->=*
	expr4 <	 expr4		smaller than		*expr-<*
	expr4 <= expr4		smaller than or equal	*expr-<=*
	expr4 =~ expr4		regexp matches		*expr-=~*
	expr4 !~ expr4		regexp doesn't match	*expr-!~*

When comparing a String with a Number, the String is converted to a Number,
and the comparison is done on Numbers.

When comparing two Strings, this is done with strcmp().  This results in the
mathematical difference, not necessarily the alphabetical difference in the
local language.

The "=~" and "!~" operators match the lefthand argument with the righthand
argument, which is used as a pattern.  See |pattern| for what a pattern is.
This matching is always done like 'magic' was set, no matter what the actual
value of 'magic' is.  This makes scripts portable.  The value of 'ignorecase'
does matter though.  To avoid backslashes in the regexp pattern to be doubled,
use a single-quote string, see |literal-string|.


expr4 and expr5						*expr4* *expr5*
---------------
	expr5 +	 expr5 ..	number addition		*expr-+*
	expr5 -	 expr5 ..	number subtraction	*expr--*
	expr5 .	 expr5 ..	string concatenation	*expr-.*

	expr6 *	 expr6 ..	number multiplication	*expr-star*
	expr6 /	 expr6 ..	number division		*expr-/*
	expr6 %	 expr6 ..	number modulo		*expr-%*

For all, except ".", Strings are converted to Numbers.

Note the difference between "+" and ".":
	"123" + "456" = 579
	"123" . "456" = "123456"

When the righthand side of '/' is zero, the result is 0xfffffff.
When the righthand side of '%' is zero, the result is 0.


expr6							*expr6*
-----
	! expr6			logical NOT		*expr-!*
	- expr6			unary minus		*expr-unary--*

For '!' non-zero becomes zero, zero becomes one.
For '-' the sign of the number is changed.

A String will be converted to a Number first.

These two can be repeated and mixed.  Examples:
    !-1	    == 0
    !!8	    == 1
    --9	    == 9


expr7							*expr7*
-----
	expr8[expr1]		index in String		*expr-[]*

This results in a String that contains the expr1'th single character from
expr8.  expr8 is used as a String, expr1 as a Number.

Note that index zero gives the first character.  This is like it works in C.
Careful: column numbers start with one!  Example, to get the character under
the cursor:
>   c = getline(line("."))[col(".") - 1]

If the length of the String is less than the index, the result is an empty
String.

							*expr8*
number
------
	number			number constant		*expr-number*

Decimal, Hexadecimal (starting with 0x or 0X), or Octal (starting with 0).


string							*expr-string*
------
	"string"		string constant		*expr-quote*

Note that double quotes are used.

A string constant accepts these special characters:
	\...	three-digit octal number (e.g., "\316")
	\..	two-digit octal number (must be followed by non-digit)
	\.	one-digit octal number (must be followed by non-digit)
	\x..	two-character hex number (e.g., "\x1f")
	\x.	one-character hex number (must be followed by non-hex)
	\X..	same as \x..
	\X.	same as \x.
	\b	backspace <BS>
	\e	escape <Esc>
	\f	formfeed <FF>
	\n	newline <NL>
	\r	return <CR>
	\t	tab <Tab>
	\\	backslash
	\"	double quote
	\<xxx>	Special key named "xxx".  e.g. "\<C-W>" for CTRL-W.

Note that "\000" and "\x00" force the end of the string.


literal-string						*literal-string*
---------------
	'string'		literal string constant		*expr-'*

Note that single quotes are used.

This string is taken literally.  No backslashes are removed or have a special
meaning.  A literal-string cannot contain a single quote.  Use a normal string
for that.


option							*expr-option*
------
	&option			option value

Any option name can be used here.  See |options|.


register						*expr-register*
--------
	@r			contents of register 'r'

The result is the contents of the named register, as a single string.
Newlines are inserted where required.  To get the contents of the unnamed
register use @@.  The '=' register can not be used here.  See |registers| for
an explanation of the available registers.


nesting							*expr-nesting*
-------
	(expr1)			nested expression


environment variable					*expr-env*
--------------------
	$VAR			environment variable

The String value of any environment variable.  When it is not defined, the
result is an empty string.


internal variable					*expr-variable*
-----------------
	variable		internal variable
See below |internal-variables|.


function call						*expr-function*
-------------
	function(expr1, ...)	function call
See below |functions|.


==============================================================================
3. Internal variable					*internal-variables*

An internal variable name can be made up of letters, digits and '_'.  But it
cannot start with a digit.

An internal variable is created with the ":let" command |:let|.
An internal variable is destroyed with the ":unlet" command |:unlet|.
Using a name that isn't an internal variable, or an internal variable that has
been destroyed, results in an error.

A variable name that is preceded with "b:" is local to the current buffer.
A variable name that is preceded with "w:" is local to the current window.
Inside functions global variables are accessed with "g:".

Predefined variables:
						    *count-variable*
count		The count given for the last Normal mode command.  Can be used
		to get the count before a mapping.  Example:
>	:map _x :<C-U>echo "the count is " . count<CR>
		Note: The <C-U> is required to remove the line range that you
		get when typing ':' after a count.  read-only.

						    *errmsg-variable*
errmsg		Last given error message.  It's allowed to set this variable.
		Example:
>	:let errmsg = ""
>	:next
>	:if (errmsg != "")
>	:  ...

						    *shell_error-variable*
shell_error	Result of the last shell command.  When non-zero, the last
		shell command had an error.  When zero, there was no problem.
		This only works when the shell returns the error code to Vim.
		The value -1 is often used when the command could not be
		executed.
		Example:
>	:!mv foo bar
>	:if shell_error
>	:  echo 'could not rename "foo" to "bar"!'
>	:endif

						    *this_session-variable*
this_session	Full filename of the last loaded or saved session file.  See
		|:mksession|.

						    *version-variable*
version		Version number of Vim: Major version number times 100 plus
		minor version number.  Version 5.0 is 500.  Version 5.1 (5.01)
		is 501.  Read-only.

==============================================================================
4. Builtin Functions					*functions*

USAGE				RESULT	DESCRIPTION	~

argc()				Number  number of files in the argument list
argv({nr})			String  {nr} entry of the argument list
browse({save}, {title}, {initdir}, {default})
				String	put up a file requester
bufexists({expr})		Number	TRUE if a buffer {exp} exists
bufname({expr})			String	Name of the buffer {expr}
bufnr({expr})			Number	Number of the buffer {expr}
char2nr({expr})			Number  ASCII value of first char in {expr}
col({expr})			Number	column nr of cursor or mark
confirm({msg}, {choices}, {default})
				Number	number of choice picked by user
delete({fname})			Number	delete file {fname}
escape({string}, {chars})	String	escape {chars} in {string} with '\'
exists({var})			Number	TRUE if {var} exists
expand({expr})			String	expand file wildcards in {expr}
filereadable({file})		Number	TRUE if {file} is a readable file
fnamemodify({fname}, {mods})	String	modify file name
getcwd()			String  the current working directory
getline({lnum})			String	line {lnum} from current buffer
has({feature})			Number	TRUE if feature {feature} supported
hlexists({name})		Number	TRUE if highlight group {name} exists
hlID({name})			Number  syntax ID of highlight group {name}
hostname()			String	name of the machine vim is running on
input({prompt})			String	get input from the user
isdirectory({directory})	Number	TRUE if {directory} is a directory
line({expr})			Number	line nr of cursor, last line or mark
match({expr}, {pat})		Number	position where {pat} matches in {expr}
matchend({expr}, {pat})		Number	position where {pat} ends in {expr}
matchstr({expr}, {pat})		String	match of {pat} in {expr}
nr2char({expr})			String	single char with ASCII value {expr}
setline({lnum}, {line})		Number	Set line {lnum} to {line}
strftime({expr})		String	current time in specified format
strlen({expr})			Number	length of the String {expr}
strpart({src}, {start}, {len})	String	{len} characters of {src} at {start}
synID({line}, {col}, {trans})	Number  syntax ID at {line} and {col}
synIDattr({synID}, {what})	String  attribute {what} of syntax ID {synID}
synIDtrans({synID})		Number  translated syntax ID of {synID}
substitute({expr}, {pat}, {sub}, {flags})
				String	all {pat} in {expr} replaced with {sub}
tempname()			String	name for a temporary file
virtcol({expr})			Number	screen column of cursor or mark
winbufnr({nr})			Number	buffer number of window {nr}
winheight({nr})			Number	height of window {nr}
winnr()				Number	number of current window

							*argc()*
argc()		The result is the number of files in the argument list.  See
		|arglist|.

							*argv()*
argv({nr})	The result is the {nr}th file in the argument list.  See
		|arglist|.  "argv(0)" is the first one.  Example:
>	let i = 0
>	while i < argc()
>	  let f = substitute(argv(i), '\([. ]\)', '\\&', 'g')
>	  exe 'amenu Arg.' . f . ' :e ' . f . '<CR>'
>	  let i = i + 1
>	endwhile

							*browse()*
browse({save}, {title}, {initdir}, {default})
		Put up a file requester.  This only works when "has("browse")"
		returns non-zero (only in some GUI versions).
		The input fields are:
		    {save}	when non-zero, select file to write
		    {title}	title for the requester
		    {initdir}	directory to start browsing in
		    {default}	default file name
		When the "Cancel" button is hit, something went wrong, or
		browsing is not possible, an empty string is returned.

							*bufexists()*
bufexists({var})
		The result is a Number, which is non-zero if a buffer called
		{var} exists.  If the {var} argument is a string it must match
		a buffer name exactly.  If the {var} argument is a number
		buffer numbers are used.  Use "bufexists(0)" to test for the
		existence of an alternate file name.
							*buffer_exists()*
		Obsolete name: buffer_exists().

							*bufname()*
bufname({expr})
		The result is the name of a buffer, as it is displayed by the
		":ls" command.
		If {expr} is a Number, that buffer number's name is given.
		Number zero is the alternate buffer for the current window.
		If {expr} is a String, it is used as a regexp pattern to match
		with the buffer names.  When there is more than one match an
		empty string is returned.  "" or "%" can be used for the
		current buffer, "#" for the alternate buffer.
		If the {expr} is a String, but you want to use it as a buffer
		number, force it to be a Number by adding zero to it:
>			echo bufname("3" + 0)
		If the buffer doesn't exist, or doesn't have a name, an empty
		string is returned.
>  bufname("#")			alternate buffer name
>  bufname(3)			name of buffer 3
>  bufname("%")			name of current buffer
>  bufname("file2")		name of buffer where "file2" matches.
							*buffer_name()*
		Obsolete name: buffer_name().

							*bufnr()*
bufnr({expr})	The result is the number of a buffer, as it is displayed by
		the ":ls" command.  For the use of {expr}, see bufname()
		above.  If the buffer doesn't exist, -1 is returned.
		bufnr("$") is the last buffer:
>  :let last_buffer = bufnr("$")
		The result is a Number, which is the highest buffer number
		of existing buffers.  Note that not all buffers with a smaller
		number necessarily exist, because ":bdel" may have removed
		them.  Use bufexists() to test for the existence of a buffer.
							*buffer_number()*
		Obsolete name: buffer_number().
							*last_buffer_nr()*
		Obsolete name for bufnr("$"): last_buffer_nr().

							*char2nr()*
char2nr({expr})
		Return ASCII value of the first char in {expr}.  Examples:
>			char2nr(" ")		returns 32
>			char2nr("ABC")		returns 65

							*col()*
col({expr})	The result is a Number, which is the column of the file
		position given with {expr}.  The accepted positions are:
		    .	    the cursor position
		    'x	    position of mark x (if the mark is not set, 0 is
			    returned)
		Note that only marks in the current file can be used.
		Examples:
>			col(".")		column of cursor
>			col("'t")		column of mark t
>			col("'" . markname)	column of mark markname
		The first column is 1.  0 is returned for an error.

							*confirm()*
confirm({msg}, {choices}[, {default} [, {type}]])
		Note: confirm() is only supported when compiled with dialog
		support, see |+dialog_con|.
		{msg} is displayed in a |dialog| with {choices} as the
		alternatives.  {default} is the number of the choice that is
		made if the user hits <CR>.  If {default} is omitted, 0 is
		used.
		{msg} is a String, use '\n' to include a newline.
		{choices} is a String, with the individual choices separated
		by '\n', e.g.
>			"Yes\nNo\nCancel"
		By default, the first letter of each choice is used as the
		shortcut key; in the above example the keys y, n, and c would
		choose the respective option.  To override this, put a '&'
		before the letter you want to use:
>			"Save\nSave &All"
		The optional {type} argument gives the type of dialog.  This
		is only used for the icon of the Win32 GUI.  It can be one of
		these values: "Error", "Question", "Info", "Warning" or
		"Generic".  Only the first character is relevant.
		If the user aborts the dialog by pressing <Esc>, CTRL-C,
		or another valid interrupt key, confirm() returns 0.

		An example:
>   :let choice = confirm("What do you want?", "Apples\nOranges\nBananas", 2)
>   :if choice == 0
>   :	echo "make up your mind!"
>   :elseif choice == 3
>   :	echo "tasteful"
>   :else
>   :	echo "I prefer bananas myself."
>   :endif
		In a GUI dialog, buttons are used.  The layout of the buttons
		depends on the 'confirm' option.  If it is "vertical", the
		buttons are always put vertically.  Otherwise,  confirm()
		tries to put the buttons in one horizontal line.  If they
		don't fit, a vertical layout is used.

							*delete()*
delete({fname})	Deletes the file by the name {fname}.  The result is a Number,
		which is 0 if the file was deleted successfully, and non-zero
		when the deletion failed.

							*escape()*
escape({string}, {chars})
		Escape the characters in {chars} that occur in {string} with a
		backslash.  Example:
>			:echo escape('c:\program files\vim', ' \')
		results in:
>			c:\\program\ files\\vim 

							*exists()*
exists({expr})	The result is a Number, which is 1 if {var} is defined, zero
		otherwise.  The {expr} argument is a string, which contains
		one of these:
			&option-name	  Vim option
			$ENVNAME	  environment variable (could also be
					  done by comparing with an empty
					  string)
			varname		  internal variable (see
					  |internal-variables|).

		Examples:
>			exists("&shortname")
>			exists("$HOSTNAME")
>			exists("bufcount")
		Note that the argument must be a string, not the name of the
		variable itself!  This doesn't check for existence of the
		"bufcount" variable, but gets the contents of "bufcount", and
		checks if that exists:
			exists(bufcount)

							*expand()*
expand({expr})	Expand the file wildcards in {expr}.  The result is a String.
		When there are several matches, they are separated by <NL>
		characters.  [Note: in version 5.0 a space was used, which
		caused problems when a file name contains a space]
		For Unix, backticks can be used to get the output of any
		command.  Example:
>			:let tagfiles = expand("`find . -name tags -print`")
>			:let &tags = substitute(tagfiles, "\n", ",", "g")

		If the expansion fails, the result is an empty string.

		When the result of {expr} starts with '%', '#' or '<', the
		expansion is done like for the |cmdline-special| variables
		with their associated modifiers.  Here is a short overview:

		%			current file name
		#			alternate file name
		#n			alternate file name n
		<cfile>			file name under the cursor
		<afile>			autocmd file name
		<abuf>			autocmd buffer number
		<sfile>			sourced script file name
		<cword>			word under the cursor
		<cWORD>			WORD under the cursor
	Modifiers:
		:p			expand to full path
		:h			head (last path component removed)
		:t			tail (last path component only)
		:r			root (one extension removed)
		:e			extension only

		Example:
>			:let &tags = expand("%:p:h") . "/tags"

		There cannot be white space between the variables and the
		following modifier.  The |fnamemodify()| function can be used
		to modify normal file names.

		When using '%' or '#', and the current or alternate file name
		is not defined, an empty string is used.  Using "%:p" in a
		buffer with no name, results in the current directory, with a
		'/' added.

							*filereadable()*
filereadable({file})
		The result is a Number, which is TRUE when a file with the
		name {file} exists, and can be read.  If {file} doesn't exist,
		or is a directory, the result is FALSE.  {file} is any
		expression, which is used as a String.
							*file_readable()*
		Obsolete name: file_readable().

							*fnamemodify()*
fnamemodify({fname}, {mods})
		Modify file name {fname} accoding to {mods}.  {mods} is a
		string of characters like it is used for file names on the
		command line.  See |filename-modifiers|.
		Example:
>			:echo fnamemodify("main.c", ":p:h")
		results in:
>			/home/mool/vim/vim/src/

							*getcwd()*
getcwd()        The result is a String, which is the name of the current
		working directory.

							*getline()*
getline({lnum}) The result is a String, which is line {lnum} from the current
		buffer.  Example:
>			getline(1)
		When {lnum} is a String that doesn't start with a
		digit, line() is called to translate the String into a Number.
		To get the line under the cursor:
>			getline(".")
		When {lnum} is smaller than 1 or bigger than the number of
		lines in the buffer, an empty string is returned.

							*has()*
has({feature})	The result is a Number, which is 1 if the feature {feature} is
		supported, zero otherwise.  The {feature} argument is a
		string.  See |feature-list| below.

							*hlexists()*
hlexists({name})
		The result is a Number, which is non-zero if a highlight group
		called {name} exists.  This is when the group has been
		defined in some way.  Not necessarily when highlighting has
		been defined for it, it may also have been used for a syntax
		item.
							*highlight_exists()*
		Obsolete name: highlight_exists().

							*hlID()*
hlID({name})	The result is a Number, which is the ID of the highlight group
		with name {name}.  When the highlight group doesn't exist,
		zero is returned.
		This can be used to retrieve information about the highlight
		group.  For example, to get the background color of the
		"Comment" group:
>	:echo synIDattr(synIDtrans(hlID("Comment")), "bg")
							*highlightID()*
		Obsolete name: highlightID().

							*hostname()*
hostname()
		The result is a String, which is the name of the machine on
		which Vim is currently running. Machine names greater than
		256 characters long are truncated.

input({prompt})						*input()*
		The result is a String, which is whatever the user typed on
		the command-line.  The parameter is either a prompt string, or
		a blank string (for no prompt).  A '\n' can be used in the
		prompt to start a new line.  The highlighting set with
		|:echohl| is used for the prompt.  The input is entered just
		like a command-line, with the same editing commands and
		mappings.  There is a separate history for lines typed for
		input().

		Example:
>	:let choice = input("What is your choice? ")

							*isdirectory()*
isdirectory({directory})
		The result is a Number, which is TRUE when a directory with
		the name {directory} exists.  If {directory} doesn't exist, or
		isn't a directory, the result is FALSE.  {directory} is any
		expression, which is used as a String.

							*line()*
line({expr})	The result is a Number, which is the line number of the file
		position given with {expr}.  The accepted positions are:
		    .	    the cursor position
		    $	    the last line in the current buffer
		    'x	    position of mark x (if the mark is not set, 0 is
			    returned)
		Note that only marks in the current file can be used.
		Examples:
>			line(".")		line number of the cursor
>			line("'t")		line number of mark t
>			line("'" . marker)	line number of mark marker

							*match()*
match({expr}, {pat})
		The result is a Number, which gives the index in {expr} where
		{pat} matches.  A match at the first character returns zero.
		If there is no match -1 is returned.  Example:
>			:echo match("testing", "ing")
		results in "4".
		See |pattern| for the patterns that are accepted.
		The 'ignorecase' option is used to set the ignore-caseness of
		the pattern.  'smartcase' is NOT used.

							*matchend()*
matchend({expr}, {pat})
		Same as match(), but return the index of first character after
		the match.  Example:
>			:echo matchend("testing", "ing")
		results in "7".

							*matchstr()*
matchstr({expr}, {pat})
		Same as match(), but return the matched string.  Example:
>			:echo matchstr("testing", "ing")
		results in "ing".
		When there is no match "" is returned.

							*nr2char()*
nr2char({expr})
		Return a string with a single chararacter, which has the ASCII
		value {expr}.  Examples:
>			nr2char(64)		returns "@"
>			nr2char(32)		returns " "

							*setline()*
setline({lnum}, {line})
		Set line {lnum} of the current buffer to {line}.  If this
		succeeds, 0 is returned.  If this fails (most likely because
		{lnum} is invalid) 1 is returned.  Example:
>			:call setline(5, strftime("%c"))

							*strftime()*
strftime({format})
		The result is a String, which is the current date and time, as
		specified by the {format} string.  See the manual page of the
		C function strftime() for the format.  The maximum length of
		the result is 80 characters.  Examples:
>		  :echo strftime("%c")		   Sun Apr 27 11:49:23 1997
>		  :echo strftime("%Y %b %d %X")	   1997 Apr 27 11:53:25
>		  :echo strftime("%y%m%d %T")	   970427 11:53:55
>		  :echo strftime("%H:%M")	   11:55

							*strlen()*
strlen({expr})	The result is a Number, which is the length of the String
		{expr}.

							*strpart()*
strpart({src}, {start}, {len})
		The result is a String, which is part of {src},
		starting from character {start}, with the length {len}.
		When non-existing characters are included, this doesn't result
		in an error, the characters are simply omitted.
>			strpart("abcdefg", 3, 2)    == "de"
>			strpart("abcdefg", -2, 4)   == "ab"
>			strpart("abcdefg", 5, 4)    == "fg"
		Note: To get the first character, {start} must be 0.  For
		example, to get three characters under and after the cursor:
>			strpart(getline(line(".")), col(".") - 1, 3)

							*synID()*
synID({line}, {col}, {trans})
		The result is a Number, which is the syntax ID at the position
		{line} and {col} in the current window.
		The syntax ID can be used with |synIDattr()| and
		|synIDtrans()| to obtain syntax information about text.
		{col} is 1 for the leftmost column, {line} is 1 for the first
		line.
		When {trans} is non-zero, transparent items are reduced to the
		item that they reveal.  This is useful when wanting to know
		the effective color.  When {trans} is zero, the transparent
		item is returned.  This is useful when wanting to know which
		syntax item is effective (e.g. inside parens).
		Warning: This function can be very slow.  Best speed is
		obtained by going through the file in forward direction.

		Example (echos the name of the syntax item under the cursor):
>			:echo synIDattr(synID(line("."), col("."), 1), "name")

							*synIDattr()*
synIDattr({synID}, {what} [, {mode}])
		The result is a String, which is the {what} attribute of
		syntax ID {synID}.  This can be used to obtain information
		about a syntax item.
		{mode} can be "gui", "cterm" or "term", to get the attributes
		for that mode.  When {mode} is omitted, or an invalid value is
		used, the attributes for the currently active highlighting are
		used (GUI, cterm or term).
		Use synIDtrans() to follow linked highlight groups.
		{what}		result
		"name"		the name of the syntax item
		"fg"		foreground color (GUI: color name, cterm:
				color number as a string, term: empty string)
		"bg"		background color (like "fg")
		"fg#"		like "fg", but name in "#RRGGBB" form
		"bg#"		like "bg", but name in "#RRGGBB" form
		"bold"		"1" if bold
		"italic"	"1" if italic
		"reverse"	"1" if reverse
		"inverse"	"1" if inverse (= reverse)
		"underline"	"1" if underlined

		When the GUI is not running or the cterm mode is asked for,
		"fg#" is equal to "fg" and "bg#" is equal to "bg".

		Example (echos the color of the syntax item under the cursor):
>	:echo synIDattr(synIDtrans(synID(line("."), col("."), 1)), "fg")

							*synIDtrans()*
synIDtrans({synID})
		The result is a Number, which is the translated syntax ID of
		{synID}.  This is the syntax group ID of what is being used to
		highlight the character.  Highlight links are followed.

							*substitute()*
substitute({expr}, {pat}, {sub}, {flags})
		The result is a String, which is a copy of {expr}, in which
		the first match of {pat} is replaced with {sub}.  This works
		like the ":substitute" command (without any flags).  But the
		'magic' option is ignored, the {pat} is always processed as if
		'magic' is set (to make scripts portable).  And a "~" in {sub}
		is not replaced with the previous {sub}.
		When {pat} does not match in {expr}, {expr} is returned
		unmodified.
		When {flags} is "g", all matches of {pat} in {expr} are
		replaced.  Otherwise {flags} should be "".
		Example:
>			:let &path = substitute(&path, ",\\=[^,]*$", "", "")
		This removes the last component of the 'path' option.
>			:echo substitute("testing", ".*", "\\U\\0", "")
		results in "TESTING".

							*tempname()*
tempname()
		The result is a String, which is the name of a file that
		doesn't exist.  It can be used for a temporary file.  The name
		is different for each least 26 consecutive calls.  Example:
>			let tmpfile = tempname()
>			exe "redir > " . tmpfile

							*virtcol()*
virtcol({expr})
		The result is a Number, which is the screen column of the file
		position given with {expr}.  That is, the last screen position
		occupied by the character at that position, when the screen
		would be of unlimited width.  When there is a <Tab> at the
		position, the returned Number will be the column at the end of
		the <Tab>.  For example, for a <Tab> in column 1, with 'ts'
		set to 8, it returns 8;
		The accepted positions are:
		    .	    the cursor position
		    'x	    position of mark x (if the mark is not set, 0 is
			    returned)
		Note that only marks in the current file can be used.
		Examples:
>  virtcol(".")	    with text "foo^Lbar", with cursor on the "^L", returns 5
>  virtcol("'t")    with text "    there", with 't at 'h', returns 6
		The first column is 1.  0 is returned for an error.

							*winbufnr()*
winbufnr({nr})	The result is a Number, which is the number of the buffer
		associated with window {nr}. When {nr} is zero, the number of
		the buffer in the current window is returned.  When window
		{nr} doesn't exist, -1 is returned.
		Example:
>  echo "The file in the current window is " . bufname(winbufnr(0))

							*winheight()*
winheight({nr})
		The result is a Number, which is the height of window {nr}.
		When {nr} is zero, the height of the current window is
		returned.  When window {nr} doesn't exist, -1 is returned.
		An existing window always has a height of zero or more.
		Examples:
>  echo "The current window has " . winheight(0) . " lines."

							*winnr()*
winnr()		The result is a Number, which is the number of the current
		window.  The top window has number 1.

							*feature-list*
There are two types of features:
1.  Features that are only supported when they have been enabled when Vim
    was compiled |+feature-list|.  Example:
>		:if has("cindent")
2.  Features that are only supported when certain conditions have been met.
    Example:
>		:if has("gui_running")

all_builtin_terms	Compiled with all builtin terminals enabled.
amiga			Amiga version of Vim.
arp			Compiled with ARP support (Amiga).
autocmd			Compiled with autocommands support.
beos			BeOS version of Vim.
browse			Compiled with |:browse| support, and browse() will
			work.
builtin_terms		Compiled with some builtin terminals.
cindent			Compiled with 'cindent' support.
cscope			Compiled with |cscope| support.
compatible		Compiled to be very Vi compatible.
debug			Compiled with "DEBUG" defined.
dialog_con		Compiled with console dialog support.
dialog_gui		Compiled with GUI dialog support.
digraphs		Compiled with support for digraphs.
dos32			32 bits DOS (DJGPP) version of Vim.
dos16			16 bits DOS version of Vim.
emacs_tags		Compiled with support for Emacs tags.
eval			Compiled with expression evaluation support.  Always
			true, of course!
ex_extra		Compiled with extra Ex commands |+ex_extra|.
extra_search		Compiled with support for |'incsearch'| and
			|'hlsearch'|
farsi			Compiled with Farsi support |farsi|.
file_in_path		Compiled with support for |gf| and |<cfile>|
filetype		Compiled with support for filetypes |+filetype|
find_in_path		Compiled with support for include file searches
			|+find_in_path|.
fname_case		Case in file names matters (for Amiga, MS-DOS, and
			Windows this is not present).
fork			Compiled to use fork()/exec() instead of system().
gui			Compiled with GUI enabled.
gui_athena		Compiled with Athena GUI.
gui_beos		Compiled with BeOs GUI.
gui_mac			Compiled with Macintosh GUI.
gui_motif		Compiled with Motif GUI.
gui_win32		Compiled with MS Windows Win32 GUI.
gui_win32s		idem, and Win32s system being used (Windows 3.1)
gui_running		Vim is running in the GUI, or it will start soon.
insert_expand		Compiled with support for CTRL-X expansion commands in
			Insert mode.
langmap			Compiled with 'langmap' support.
lispindent		Compiled with support for lisp indenting.
mac			Macintosh version of Vim.
modify_fname		Compiled with file name modifiers. |filename-modifiers|
mouse			Compiled with support mouse.
mouse_dec		Compiled with support for Dec terminal mouse.
mouse_netterm		Compiled with support for netterm mouse.
mouse_xterm		Compiled with support for xterm mouse.
multi_byte		Compiled with support for Korean et al.
multi_byte_ime		Compiled with support for IME input method
ole			Compiled with OLE automation support for Win32.
perl			Compiled with Perl interface.
python			Compiled with Python interface.
quickfix		Compiled with |quickfix| support.
rightleft		Compiled with 'rightleft' support.
showcmd			Compiled with 'showcmd' support.
smartindent		Compiled with 'smartindent' support.
sniff			Compiled with SniFF interface support.
syntax			Compiled with syntax highlighting support.
syntax_items		There are active syntax highlighting items for the
			current buffer.
system			Compiled to use system() instead of fork()/exec().
tag_binary		Compiled with binary searching in tags files
			|tag-binary-search|.
tag_old_static		Compiled with support for old static tags
			|tag-old-static|.
tag_any_white		Compiled with support for any white characters in tags
			files |tag-any-white|.
tcl			Compiled with Tcl interface.
terminfo		Compiled with terminfo instead of termcap.
textobjects		Compiled with support for |text-objects|.
tgetent			Compiled with tgetent support, able to use a termcap
			or terminfo file.
unix			Unix version of Vim.
user-commands		User-defined commands.
viminfo			Compiled with viminfo support.
vms			VMS version of Vim.
wildignore		Compiled with 'wildignore' option
win32			Win32 version of Vim (Windows 95/NT)
writebackup		Compiled with 'writebackup' default on.
xterm_save		Compiled with support for saving and restoring the
			xterm screen.
x11			Compiled with X11 support.

==============================================================================
5. Defining functions					*user-functions*

New functions can be defined.  These can be called with "Name()", just like
builtin functions.  The name must start with an uppercase letter, to avoid
confusion with builtin functions.

							*:fu* *:function*
:fu[nction]		List all functions and their arguments.

:fu[nction] {name}	List function {name}.

:fu[nction][!] {name}([arguments]) [range] [abort]
			Define a new function by the name {name}.  The name
			must be made of alphanumeric characters and '_', and
			must start with a capital.
			An argument can be defined by giving its name.  In the
			function this can then be used as "a:name" ("a:" for
			argument).
			Several arguments can be given, separated by commas.
			Finally, an argument "..." can be specified, which
			means that more arguments may be following.  In the
			function they can be used as "a:1", "a:2", etc.  "a:0"
			is set to the number of extra arguments (which can be
			0).
			When not using "...", the number of arguments in a
			function call must be equal the number of named
			arguments.  When using "...", the number of arguments
			may be larger.
			The body of the function follows in the next lines,
			until ":endfunction".
			When a function by this name already exists and [!] is
			not used an error message is given.  When [!] is used,
			an existing function is silently replaced.
			When the [range] argument is added, the function is
			expected to take care of a range itself.  The range is
			passed as "a:firstline" and "a:lastline".  If [range]
			is excluded, a ":call" with a range will call the
			function for each line, with the cursor on the start
			of each line.
			When the [abort] argument is added, the function will
			abort as soon as an error is detected.
                        The last used search pattern and the redo command "."
                        will not be changed by the function.

							*:endf* *:endfunction*
:endf[unction]		The end of a function definition.

							*:delf* *:delfunction*
:delf[unction] {name}	Delete function {name}.

							*:retu* *:return*
:retu[rn] [expr]	Return from a function.  When "[expr]" is given, it is
			evaluated and returned as the result of the function.
			If "[expr]" is not given, the number 0 is returned.
			When a function ends without an explicit ":return",
			the number 0 is returned.
			Note that there is no check for unreachable lines,
			thus there is no warning if commands follow ":return".

Inside a function variables can be used.  These are local variables, which
will disappear when the function returns.  Global variables need to be
accessed with "g:".

Example:
>  :function Table(title, ...)
>  :  echohl Title
>  :  echo a:title
>  :  echohl None
>  :  let idx = 1
>  :  while idx <= a:0
>  :    exe "echo a:" . idx
>  :    let idx = idx + 1
>  :  endwhile
>  :  return idx
>  :endfunction

This function can then be called with:
>  let lines = Table("Table", "line1", "line2")
>  let lines = Table("Empty Table")

To return more than one value, pass the name of a global variable:
>  :function Compute(n1, n2, divname)
>  :  if a:n2 == 0
>  :    return "fail"
>  :  endif
>  :  exe "let " . a:divname . " = ". a:n1 / a:n2
>  :  return "ok"
>  :endfunction

This function can then be called with:
>  :let success = Compute(13, 1324, "div")
>  :if success == "ok"
>  :  echo div
>  :endif

							*:cal* *:call*
:[range]cal[l] {name}([arguments])
		Call a function.  The name of the function and its arguments
		are as before.
		Without a range and for functions that accept a range, the
		function is called once, with the cursor at the current
		position.
		When a range is given and the function doesn't handle it
		itself, the function is executed for each line in the range,
		with the cursor in the first column of that line.  The cursor
		is left at the last line (possibly moved by the last function
		call).  The arguments are re-evaluated for each line.  Thus
		this works:

>	:function Mynumber(arg)
>	:  echo line(".") . " " . a:arg
>	:endfunction
>	:1,5call Mynumber(getline("."))

The recursiveness of user functions is restricted with the |'maxfuncdepth'|
option.

==============================================================================
6. Commands						*expression-commands*

:let {var-name} = {expr1}				*:let*
			Set internal variable {var-name} to the result of the
			expression {expr1}.  The variable will get the type
			from the {expr}.  if {var-name} didn't exist yet, it
			is created.

:let ${env-name} = {expr1}			*:let-environment* *:let-$*
			Set environment variable {env-name} to the result of
			the expression {expr1}.  The type is always String.

:let @{reg-name} = {expr1}			*:let-register* *:let-@*
			Write the result of the expression {expr1} in register
			{reg-name}.  {reg-name} must be a single letter, and
			must be the name of a writable register (see
			|registers|).  "@@" can be used for the unnamed
			register.  If the result of {expr1} ends in a <CR> or
			<NL>, the register will be linewise, otherwise it will
			be set to characterwise.

:let &{option-name} = {expr1}			*:let-option* *:let-star*
			Set option {option-name} to the result of the
			expression {expr1}.  The type of the option is always
			used.

							*:unlet* *:unl*
:unl[et][!] {var-name} ...
			Remove the internal variable {var-name}.  Several
			variable names can be given, they are all removed.
			With [!] no error message is given for non-existing
			variables.

:if {expr1}						*:if* *:endif* *:en*
:en[dif]		Execute the commands until the next matching ":else"
			or ":endif" if {expr1} evaluates to non-zero.

			From Vim version 4.5 until 5.0, every Ex command in
			between the ":if" and ":endif" is ignored.  These two
			commands were just to allow for future expansions in a
			backwards compatible way.  Nesting was allowed.  Note
			that any ":else" or ":elseif" was ignored, the "else"
			part was not executed either.

			You can use this to remain compatible with older
			versions:
>				:if version >= 500
>				:  version-5-specific-commands
>				:endif

							*:else* *:el*
:el[se]			Execute the commands until the next matching ":else"
			or ":endif" if they previously were not being
			executed.

							*:elseif* *:elsei*
:elsei[f] {expr1}	Short for ":else" ":if", with the addition that there
			is no extra ":endif".

:wh[ile] {expr1}			*:while* *:endwhile* *:wh* *:endw*
:endw[hile]		Repeat the commands between ":while" and ":endwhile",
			as long as {expr1} evaluates to non-zero.
			When an error is detected from a command inside the
			loop, execution continues after the "endwhile".

		NOTE: The ":append" and ":insert" commands don't work properly
		inside a ":while" loop.

							*:continue* *:con*
:con[tinue]		When used inside a ":while", jumps back to the
			":while".

							*:break* *:brea*
:brea[k]		When used inside a ":while", skips to the command
			after the matching ":endwhile".

							*:ec* *:echo*
:ec[ho] {expr1} ..	Echoes each {expr1}, with a space in between and a
			terminating <EOL>.  Also see |:comment|.
			Example:
>		:echo "the value of 'shell' is" &shell

							*:echon*
:echon {expr1} ..	Echoes each {expr1}, without anything added.  Also see
			|:comment|.
			Example:
>		:echon "the value of 'shell' is " &shell

			Note the difference between using ":echo", which is a
			Vim command, and ":!echo", which is an external shell
			command:
>		:!echo %		--> filename
			The arguments of ":!" are expanded, see |:_%|.
>		:!echo "%"		--> filename or "filename"
			Like the previous example.  Whether you see the double
			quotes or not depends on your 'shell'.
>		:echo %			--> nothing
			The '%' is an illegal character in an expression.
>		:echo "%"		--> %
			This just echoes the '%' character.
>		:echo expand("%")	--> filename
			This calls the expand() function to expand the '%'.

							*:echoh* *:echohl*
:echoh[l] {name}	Use the highlight group {name} for the following
			":echo[n]" commands.  Example:
>		:echohl WarningMsg | echo "Don't panic!" | echohl None
			Don't forget to set the group back to "None",
			otherwise all following echo's will be highlighted.

							*:exe* *:execute*
:exe[cute] {expr1} ..	Executes the string that results from the evaluation
			of {expr1} as an Ex command.  Multiple arguments are
			concatenated, with a space in between.  Examples:
>		:execute "buffer " nextbuf
>		:execute "normal " count . "w"

			Execute can be used to append a next command to
			commands that don't accept a '|'.  Example:
>		:execute '!ls' | echo "theend"

			Note: The executed string may be any command-line, but
			you cannot start or end a "while" or "if" command.
			Thus this is illegal:
>		:execute 'while i > 5'
>		:execute 'echo "test" | break'

			It is allowed to have a "while" or "if" command
			completely in the executed string:
>		:execute 'while i < 5 | echo i | let i = i + 1 | endwhile'


							*:comment*
			":execute", ":echo" and ":echon" cannot be followed by
			a comment directly, because they see the '"' as the
			start of a string.  But, you can use '|' followed by a
			comment.  Example:
>		:echo "foo" | "this is a comment


 vim:tw=78:ts=8:sw=8:
