Mercurial > hg > octave-lyh
changeset 6666:5d4ce539004f
[project @ 2007-05-28 06:07:39 by jwe]
author | jwe |
---|---|
date | Mon, 28 May 2007 06:07:39 +0000 |
parents | cfb849d6f314 |
children | a36e4bb26943 |
files | doc/ChangeLog doc/interpreter/io.txi doc/interpreter/struct.txi scripts/strings/hex2dec.m src/ChangeLog src/ov-list.cc |
diffstat | 6 files changed, 215 insertions(+), 68 deletions(-) [+] |
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--- a/doc/ChangeLog +++ b/doc/ChangeLog @@ -1,3 +1,12 @@ +2007-05-28 Søren Hauberg <hauberg@gmail.com> + + * interpreter/io.txi: Rearrange some sections, and add + a few examples. + +2007-05-28 G. D. McBain <geordie_mcbain@yahoo.com.au> + + * interpreter/struct.txi: Doc fix. + 2007-05-23 John W. Eaton <jwe@octave.org> * liboctave/Makefile.in (TEXINFO_SOURCE): New variable.
--- a/doc/interpreter/io.txi +++ b/doc/interpreter/io.txi @@ -5,6 +5,64 @@ @node Input and Output @chapter Input and Output +Octave supports several ways of reading and writing data to or from the +prompt or a file. The most simple functions for data Input and Output +(I/O) are easy to use, but only provides a limited control of how +data is processed. For more control, a set of functions modelled +after the C standard library are also provided by Octave. + +@menu +* Basic Input and Output:: +* C-Style I/O Functions:: +@end menu + +@node Basic Input and Output +@section Basic Input and Output + +@c We could use a two-line introduction here... + +@menu +* Terminal Output:: +* Terminal Input:: +* Simple File I/O:: +@end menu + +@node Terminal Output +@subsection Terminal Output + +Since Octave normally prints the value of an expression as soon as it +has been evaluated, the simplest of all I/O functions is a simple +expression. For example, the following expression will display the +value of @samp{pi} + +@example +pi + @print{} pi = 3.1416 +@end example + +This works well as long as it is acceptable to have the name of the +variable (or @samp{ans}) printed along with the value. To print the +value of a variable without printing its name, use the function +@code{disp}. + +The @code{format} command offers some control over the way Octave prints +values with @code{disp} and through the normal echoing mechanism. + +@DOCSTRING(ans) + +@DOCSTRING(disp) + +@DOCSTRING(format) + +@DOCSTRING(print_answer_id_name) + +@menu +* Paging Screen Output:: +@end menu + +@node Paging Screen Output +@subsubsection Paging Screen Output + When running interactively, Octave normally sends any output intended for your terminal that is more than one screen long to a paging program, such as @code{less} or @code{more}. This avoids the problem of having a @@ -21,9 +79,9 @@ used to force output to be sent to the pager (or any other stream) immediately. -You can select the program to run as the pager by setting the variable -@code{PAGER}, and you can turn paging off by setting the value of the -variable @code{page_screen_output} to 0. +You can select the program to run as the pager using the @code{PAGER} +function, and you can turn paging off by using the function +@code{more}. @DOCSTRING(more) @@ -44,51 +102,6 @@ @c warning: pending computations and output may be lost @c warning: broken pipe -@menu -* Basic Input and Output:: -* C-Style I/O Functions:: -@end menu - -@node Basic Input and Output -@section Basic Input and Output - -@menu -* Terminal Output:: -* Terminal Input:: -* Simple File I/O:: -@end menu - -@node Terminal Output -@subsection Terminal Output - -Since Octave normally prints the value of an expression as soon as it -has been evaluated, the simplest of all I/O functions is a simple -expression. For example, the following expression will display the -value of pi - -@example -pi - @print{} pi = 3.1416 -@end example - -This works well as long as it is acceptable to have the name of the -variable (or @samp{ans}) printed along with the value. To print the -value of a variable without printing its name, use the function -@code{disp}. - -The @code{format} command offers some control over the way Octave prints -values with @code{disp} and through the normal echoing mechanism. - -@DOCSTRING(ans) - -@DOCSTRING(fdisp) - -@DOCSTRING(disp) - -@DOCSTRING(format) - -@DOCSTRING(print_answer_id_name) - @node Terminal Input @subsection Terminal Input @@ -117,17 +130,76 @@ @cindex loading data The @code{save} and @code{load} commands allow data to be written to and read from disk files in various formats. The default format of files -written by the @code{save} command can be controlled using the built-in -variables @code{default_save_options} and @code{save_precision}. +written by the @code{save} command can be controlled using the functions +@code{default_save_options} and @code{save_precision}. + +As an example the following code creates a 3-by-3 matrix and saves it +to the file @samp{myfile.mat}. + +@example +A = [ 1:3; 4:6; 7:9 ]; +save myfile.mat A +@end example -Note that Octave cannot yet save or load structure variables or any -user-defined types. +Once one or more variables have been saved to a file, they can be +read into memory using the @code{load} command. + +@example +load myfile.mat +A + @print{} A = + @print{} + @print{} 1 2 3 + @print{} 4 5 6 + @print{} 7 8 9 +@end example @DOCSTRING(save) -There are three variables that modify the behavior of @code{save} and -three more that control whether variables are saved when Octave exits -unexpectedly. +@DOCSTRING(load) + +There are three functions that modify the behavior of @code{save}. + +@DOCSTRING(default_save_options) + +@DOCSTRING(save_precision) + +@DOCSTRING(save_header_format_string) + +@DOCSTRING(native_float_format) + +It is possible to write data to a file in a way much similar to the +@code{disp} function for writing data to the screen. The @code{fdisp} +works just like @code{disp} except its first argument is a file pointer +as created by @code{fopen}. As an example, the following code writes +to data @samp{myfile.txt}. + +@example +fid = fopen ("myfile.txt", "w"); +fdisp (fid, "3/8 is "); +fdisp (fid, 3/8); +fclose (fid); +@end example + +@noindent +@xref{Opening and Closing Files}, for details on how to use @code{fopen} +and @code{fclose}. + +@DOCSTRING(fdisp) + +@menu +* Saving Data on Unexpected Exits:: +@end menu + +@node Saving Data on Unexpected Exits +@subsubsection Saving Data on Unexpected Exits + +If Octave for some reason exits unexpected it will by default save the +variables available in the workspace to a file in the current directory. +By default this file is named @samp{octave-core} and can be loaded +into memory with the @code{load} command. While the default behaviour +most often is reasonable it can be changed through the following +functions. @DOCSTRING(crash_dumps_octave_core) @@ -135,21 +207,12 @@ @DOCSTRING(sigterm_dumps_octave_core) -@DOCSTRING(default_save_options) - @DOCSTRING(octave_core_file_options) @DOCSTRING(octave_core_file_limit) @DOCSTRING(octave_core_file_name) -@DOCSTRING(save_precision) - -@DOCSTRING(save_header_format_string) - -@DOCSTRING(load) - -@DOCSTRING(native_float_format) @node C-Style I/O Functions @section C-Style I/O Functions @@ -198,6 +261,21 @@ @node Opening and Closing Files @subsection Opening and Closing Files +When reading data from a file it must be opened for reading first, and +likewise when writing to a file. The @code{fopen} function returns a +pointer to an open file that is ready to be read or written. Once all +data has been read from or written to the opened file it should be closed. +The @code{fclose} function does this. The following code illustrates +the basic pattern for writing to a file, but a very similar pattern is +used when reading a file. + +@example +filename = "myfile.txt"; +fid = fopen (filename, "w"); +# Do the actual I/O here... +fclose (fid); +@end example + @DOCSTRING(fopen) @DOCSTRING(fclose) @@ -205,13 +283,44 @@ @node Simple Output @subsection Simple Output +Once a file has been opened for writing a string can be written to the +file using the @code{fputs} function. The following example shows +how to write the string @samp{Free Software is needed for Free Science} +to the file @samp{free.txt}. + +@example +filename = "free.txt"; +fid = fopen (filename, "w"); +fputs (fid, "Free Software is needed for Free Science"); +fclose (fid); +@end example + @DOCSTRING(fputs) +A function much similar to @code{fputs} is available for writing data +to the screen. The @code{puts} function works just like @code{fputs} +except it doesn't take a file pointer as its input. + @DOCSTRING(puts) @node Line-Oriented Input @subsection Line-Oriented Input +To read from a file it must be opened for reading using @code{fopen}. +Then a line can be read from the file using @code{fgetl} as the following +code illustrates + +@example +fid = fopen ("free.txt"); +txt = fgetl (fid) + @print{} Free Software is needed for Free Science +fclose (fid); +@end example + +@noindent +This of course assumes that the file @samp{free.txt} exists and contains +the line @samp{Free Software is needed for Free Science}. + @DOCSTRING(fgetl) @DOCSTRING(fgets) @@ -825,6 +934,11 @@ @node Temporary Files @subsection Temporary Files +Sometimes one needs to write data to a file that is only temporary. +This is most commonly used when an external program launched from +within Octave needs to access data. When Octave exits all temporary +files will be deleted, so this step need not be executed manually. + @DOCSTRING(mkstemp) @DOCSTRING(tmpfile) @@ -834,6 +948,27 @@ @node EOF and Errors @subsection End of File and Errors +Once a file has been opened its status can be acquired. As an example +the @code{feof} functions determines if the end of the file has been +reached. This can be very useful when reading small parts of a file +at a time. The following example shows how to read one line at a time +from a file until the end has been reached. + +@example +filename = "myfile.txt"; +fid = fopen (filename, "r"); +while (! feof (fid) ) + text_line = fgetl (fid); +endwhile +fclose (fid); +@end example + +@noindent +Note that in some situations it is more efficient to read the entire +contents of a file and then process it, than it is to read it line by +line. This has the potential advantage of removing the loop in the +above code. + @DOCSTRING(feof) @DOCSTRING(ferror) @@ -854,7 +989,6 @@ @DOCSTRING(frewind) - The following example stores the current file position in the variable @code{marker}, moves the pointer to the beginning of the file, reads four characters, and then returns to the original position.
--- a/doc/interpreter/struct.txi +++ b/doc/interpreter/struct.txi @@ -140,7 +140,7 @@ @example @group -octave:2> f (rand (2) + rand (2) * I); +octave:2> f (rand (2) + rand (2) * I) ans = @{ im =
--- a/scripts/strings/hex2dec.m +++ b/scripts/strings/hex2dec.m @@ -19,7 +19,7 @@ ## -*- texinfo -*- ## @deftypefn {Function File} {} hex2dec (@var{s}) -## Returns the integer corresponding to the hexadecimal number stored +## Return the integer corresponding to the hexadecimal number stored ## in the string @var{s}. For example, ## ## @example
--- a/src/ChangeLog +++ b/src/ChangeLog @@ -1,3 +1,7 @@ +2007-05-28 G. D. McBain <geordie_mcbain@yahoo.com.au> + + * ov-list.cc (append): Doc fix. + 2007-05-28 John W. Eaton <jwe@octave.org> * pt-loop.cc (DO_ND_LOOP): Avoid parser problem with obsolete g++.
--- a/src/ov-list.cc +++ b/src/ov-list.cc @@ -404,7 +404,7 @@ DEFUN (append, args, , "-*- texinfo -*-\n\ @deftypefn {Built-in Function} {} append (@var{list}, @var{a1}, @var{a2}, @dots{})\n\ -Return a new list created by appending @var{a1}, @var{a1}, @dots{}, to\n\ +Return a new list created by appending @var{a1}, @var{a2}, @dots{}, to\n\ @var{list}. If any of the arguments to be appended is a list, its\n\ elements are appended individually. For example,\n\ \n\