From 84adefa331c4159d432d22840663c38f155cd4c1 Mon Sep 17 00:00:00 2001 From: Erlang/OTP Date: Fri, 20 Nov 2009 14:54:40 +0000 Subject: The R13B03 release. --- lib/stdlib/doc/src/io_lib.xml | 300 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 300 insertions(+) create mode 100644 lib/stdlib/doc/src/io_lib.xml (limited to 'lib/stdlib/doc/src/io_lib.xml') diff --git a/lib/stdlib/doc/src/io_lib.xml b/lib/stdlib/doc/src/io_lib.xml new file mode 100644 index 0000000000..399f968c5f --- /dev/null +++ b/lib/stdlib/doc/src/io_lib.xml @@ -0,0 +1,300 @@ + + + + +
+ + 19962009 + Ericsson AB. All Rights Reserved. + + + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + + + io_lib + + + + +
+ io_lib + IO Library Functions + +

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()] +
+ + + nl() -> chars() + Write a newline + +

Returns a character list which represents a new line + character.

+ + + + write(Term) -> + write(Term, Depth) -> chars() + Write a term + + 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() + Pretty print a term + + 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() | UnicodeList + Write formatted output + + 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 + Read formatted input + + 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} + +

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 + Re-entrant formatted reader + + 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} + +

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() + Write an atom + + Atom = atom() + + +

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

+ + + + write_string(String) -> chars() + Write a string + + String = string() + + +

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

+ + + + write_char(Integer) -> chars() + Write a character + + Integer = int() + + +

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

+ + + + indentation(String, StartIndent) -> int() + Indentation after printing string + + String = string() + StartIndent = int() + + +

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

+ + + + char_list(Term) -> bool() + Test for a list of characters + + Term = term() + + +

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

+ + + + deep_char_list(Term) -> bool() + Test for a deep list of characters + + 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() + Test for a list of printable ISO-latin-1 characters + + Term = term() + + +

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

+ + + + + -- cgit v1.2.3