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io_lib(3erl)			     Erlang Module Definition			     io_lib(3erl)

NAME
       io_lib - IO Library Functions

DESCRIPTION
       This  module  contains functions for converting to and from strings (lists of characters).
       They are used for implementing the functions in the io module. There is no guarantee  that
       the  character lists returned from some of the functions are flat, they can be deep lists.
       lists:flatten/1 can be used for flattening deep lists.

DATA TYPES
       chars() = [char() | chars()]

EXPORTS
       nl() -> chars()

	      Returns a character list which represents a new line character.

       write(Term) ->
       write(Term, Depth) -> chars()

	      Types  Term = term()
		     Depth = int()

	      Returns a character list which represents Term . The Depth (-1)  argument  controls
	      the  depth  of  the structures written. When the specified depth is reached, every-
	      thing below this level is replaced by "...". For example:

	      1> lists:flatten(io_lib:write({1,[2],[3],[4,5],6,7,8,9})).
	      "{1,[2],[3],[4,5],6,7,8,9}"
	      2> lists:flatten(io_lib:write({1,[2],[3],[4,5],6,7,8,9}, 5)).
	      "{1,[2],[3],[...],...}"

       print(Term) ->
       print(Term, Column, LineLength, Depth) -> chars()

	      Types  Term = term()
		     Column = LineLenght = Depth = int()

	      Also returns a list of characters which represents Term ,  but  breaks  representa-
	      tions  which  are longer than one line into many lines and indents each line sensi-
	      bly. It also tries to detect and output lists of printable characters  as  strings.
	      Column  is  the  starting  column(1), LineLength the maximum line length(80), and
	      Depth (-1) the maximum print depth.

       fwrite(Format, Data) ->
       format(Format, Data) -> chars() | UnicodeList

	      Types  Format = atom() | string() | binary()
		     Data = [term()]
		     UnicodeList = [Unicode]
		     Unicode = int() representing valid unicode codepoint

	      Returns a character list which represents Data formatted in accordance with  Format
	      .  See  io:fwrite/1,2,3  for  a  detailed  description  of the available formatting
	      options. A fault is generated if there is an error in the format string or argument
	      list.

	      If  (and	only  if)  the	Unicode translation modifier is used in the format string
	      (i.e. ~ts or ~tc), the resulting list may contain characters beyond the ISO-latin-1
	      character range (in other words, numbers larger than 255). If so, the result is not
	      an ordinary Erlang string(), but can well be used in any context where Unicode data
	      is allowed.

       fread(Format, String) -> Result

	      Types  Format = String = string()
		     Result  = {ok, InputList, LeftOverChars} | {more, RestFormat, Nchars, Input-
		     Stack} | {error, What}
		     InputList = chars()
		     LeftOverChars = string()
		     RestFormat = string()
		     Nchars = int()
		     InputStack = chars()
		     What = term()

	      Tries to read String in accordance with the  control  sequences  in  Format  .  See
	      io:fread/3  for  a  detailed description of the available formatting options. It is
	      assumed that String contains whole lines. It returns:

		{ok, InputList, LeftOverChars} :
		  The string was read. InputList is the list of  successfully  matched	and  read
		  items, and LeftOverChars are the input characters not used.

		{more, RestFormat, Nchars, InputStack} :
		  The string was read, but more input is needed in order to complete the original
		  format string. RestFormat is the remaining format string, NChars the number  of
		  characters scanned, and InputStack is the reversed list of inputs matched up to
		  that point.

		{error, What} :
		  The read operation failed and the parameter What gives a hint about the error.

	      Example:

	      3> io_lib:fread("~f~f~f", "15.6 17.3e-6 24.5").
	      {ok,[15.6,1.73e-5,24.5],[]}

       fread(Continuation, String, Format) -> Return

	      Types  Continuation = see below
		     String = Format = string()
		     Return = {done, Result, LeftOverChars} | {more, Continuation}
		     Result = {ok, InputList} | eof | {error, What}
		     InputList = chars()
		     What = term()()
		     LeftOverChars = string()

	      This is the re-entrant formatted reader. The continuation of the first call to  the
	      functions  must be [] . Refer to Armstrong, Virding, Williams, 'Concurrent Program-
	      ming in Erlang', Chapter 13 for a complete description of how the re-entrant  input
	      scheme works.

	      The function returns:

		{done, Result, LeftOverChars} :
		  The input is complete. The result is one of the following:

		  {ok, InputList} :
		    The  string  was read. InputList is the list of successfully matched and read
		    items, and LeftOverChars are the remaining characters.

		  eof :
		    End of file has been encountered. LeftOverChars are the input characters  not
		    used.

		  {error, What} :
		    An error occurred and the parameter What gives a hint about the error.

		{more, Continuation} :
		  More data is required to build a term. Continuation must be passed to fread/3 ,
		  when more data becomes available.

       write_atom(Atom) -> chars()

	      Types  Atom = atom()

	      Returns the list of characters needed to print the atom Atom .

       write_string(String) -> chars()

	      Types  String = string()

	      Returns the list of characters needed to print String as a string.

       write_char(Integer) -> chars()

	      Types  Integer = int()

	      Returns the list of characters needed to print a character  constant  in	the  ISO-
	      latin-1 character set.

       indentation(String, StartIndent) -> int()

	      Types  String = string()
		     StartIndent = int()

	      Returns the indentation if String has been printed, starting at StartIndent .

       char_list(Term) -> bool()

	      Types  Term = term()

	      Returns  true if Term is a flat list of characters in the ISO-latin-1 range, other-
	      wise it returns false .

       deep_char_list(Term) -> bool()

	      Types  Term = term()

	      Returns true if Term is a, possibly deep, list of  characters  in  the  ISO-latin-1
	      range, otherwise it returns false .

       printable_list(Term) -> bool()

	      Types  Term = term()

	      Returns  true if Term is a flat list of printable ISO-latin-1 characters, otherwise
	      it returns false .

Ericsson AB				  stdlib 1.17.3 			     io_lib(3erl)
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