![[Ericsson AB]](min_head.gif)
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.
chars() = [char() | 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,
everything 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 representations which are longer than
one line into many lines and indents each line sensibly. 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()
Types:
Format = string()
Data = [term()]
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.
fread(Format, String) -> Result
Types:
Format = String = string()
Result = {ok, InputList, LeftOverChars} |
{more, RestFormat, Nchars, InputStack} | {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}
InputList is the list of
successfully matched and read items, and
LeftOverChars are the input characters not used.
{more, RestFormat, Nchars, InputStack}
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}
What
gives a hint about the error.Example:
3> io_lib:fread("~f~f~f", "15.6 17.3e-6 24.5").
{ok,[15.6000,1.73000e-5,24.5000],[]}
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 Programming in
Erlang', Chapter 13 for a complete description of how the
re-entrant input scheme works.
The function returns:
{done, Result, LeftOverChars}
{ok, InputList}
InputList is the list of
successfully matched and read items, and
LeftOverChars are the remaining characters.eof
LeftOverChars are the input characters not
used.{error, What}
What gives
a hint about the error.{more, Continuation}
Continuation must be passed to fread/3,
when more data becomes available.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.
indentation(String, StartIndent) -> int()
Types:
String = string()
StartIndent = int()
Returns the indentation if String has been printed,
starting at StartIndent.
Types:
Term = term()
Returns true if Term is a flat list of
characters, otherwise it returns false.
deep_char_list(Term) -> bool()
Types:
Term = term()
Returns true if Term is a, possibly deep, list
of characters, otherwise it returns false.
printable_list(Term) -> bool()
Types:
Term = term()
Returns true if Term is a flat list of
printable characters, otherwise it returns false.