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 is used for generating flat lists.
Returns a character list which represents a new line character.
write(Term)
write(Term, Depth)
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:
> lists:flatten(io_lib:write({1,[2],[3],[4,5],6,7,8,9})).
"{1,[2],[3],[4,5],6,7,8,9}"
> lists:flatten(io_lib:write({1,[2],[3],[4,5],6,7,8,9}, 5)).
"{1,[2],[3],[4|...],6|...}"
print(Term)
print(Term, Column, LineLength, Depth)
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 the maximum print depth.
fwrite(Format, Data)
format(Format, Data)
Returns a character list which represents Data formatted
in accordance with Format. Refer to io 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.
Tries to read String in accordance with the control
sequences in Format. Refer to io 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}format_error/1.
Example:
> io_lib:fread("~f~f~f", "15.6 17.3e-6 24.5").
{ok, [15.6000, 1.73000e-5, 24.5000], []}
fread(Continuation, CharList, Format)
This is the re-entrant formatted reader. It returns:
{done, Result, LeftOverChars}{ok, InputList}InputList is the
list of successfully matched and read items, and
LeftOverChars are the remaining characters.
eofLeftOverChars are the input characters not
used.
{error,What}format_error/1.
{more, Continuation}Continuation must be passed to <c>fread/3, when more data becomes available.Returns the list of characters needed to print the atom
Atom.
Returns the list of characters needed to print
String as a string.
Returns the list of characters needed to print a character constant.
indentation(String, StartIndent)
Returns the indentation if String has been printed,
starting at Indentation.
Returns true if CharList is a list of characters,
otherwise it returns false.
Returns true if CharList is a deep list of
characters, otherwise it returns false.
Returns true if CharList is a list of printable
characters, otherwise it returns false.
The module io_lib also uses the extra modules
io_lib_format, io_lib_fread, and
io_lib_pretty. All external interfaces exist in
io_lib.
Users are strongly advised not to access the other modules directly.
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Any undocumented functions in |
The continuation of the first call to the re-entrant input 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