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[wxWidgets.git] / docs / latex / wx / ffile.tex

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% Name:        ffile.tex
%% Purpose:     wxFFile documentation
%% Author:      Vadim Zeitlin
%% Modified by:
%% Created:     14.01.02 (extracted from file.tex)
%% RCS-ID:      $Id$
%% Copyright:   (c) Vadim Zeitlin
%% License:     wxWindows license
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\section{\class{wxFFile}}\label{wxffile}

wxFFile implements buffered file I/O. This is a very small class designed to
minimize the overhead of using it - in fact, there is hardly any overhead at
all, but using it brings you automatic error checking and hides differences
between platforms and compilers. It wraps inside it a {\tt FILE *} handle used
by standard C IO library (also known as {\tt stdio}).

\wxheading{Derived from}

None.

\wxheading{Include files}

<wx/ffile.h>

\twocolwidtha{7cm}
\begin{twocollist}\itemsep=0pt%
\twocolitem{{\bf wxFromStart}}{Count offset from the start of the file}
\twocolitem{{\bf wxFromCurrent}}{Count offset from the current position of the file pointer}
\twocolitem{{\bf wxFromEnd}}{Count offset from the end of the file (backwards)}
\end{twocollist}

\latexignore{\rtfignore{\wxheading{Members}}}

\membersection{wxFFile::wxFFile}\label{wxffileconstr}

\func{}{wxFFile}{\void}

Default constructor.

\func{}{wxFFile}{\param{const char*}{ filename}, \param{const char*}{ mode = "r"}}

Opens a file with the given mode. As there is no way to return whether the
operation was successful or not from the constructor you should test the
return value of \helpref{IsOpened}{wxffileisopened} to check that it didn't
fail.

\func{}{wxFFile}{\param{FILE*}{ fp}}

Opens a file with the given file pointer, which has already been opened.

\wxheading{Parameters}

\docparam{filename}{The filename.}

\docparam{mode}{The mode in which to open the file using standard C strings.
Note that you should use {\tt "b"} flag if you use binary files under Windows
or the results might be unexpected due to automatic newline conversion done
for the text files.}

\docparam{fp}{An existing file descriptor, such as stderr.}

\membersection{wxFFile::\destruct{wxFFile}}

\func{}{\destruct{wxFFile}}{\void}

Destructor will close the file.

NB: it is not virtual so you should {\it not} derive from wxFFile!

\membersection{wxFFile::Attach}\label{wxffileattach}

\func{void}{Attach}{\param{FILE*}{ fp}}

Attaches an existing file pointer to the wxFFile object.

The descriptor should be already opened and it will be closed by wxFFile
object.

\membersection{wxFFile::Close}\label{wxffileclose}

\func{bool}{Close}{\void}

Closes the file and returns TRUE on success.

\membersection{wxFFile::Detach}\label{wxffiledetach}

\func{void}{Detach}{\void}

Get back a file pointer from wxFFile object - the caller is responsible for closing the file if this
descriptor is opened. \helpref{IsOpened()}{wxffileisopened} will return FALSE after call to Detach().

\membersection{wxFFile::fp}\label{wxffilefp}

\constfunc{FILE *}{fp}{\void}

Returns the file pointer associated with the file.

\membersection{wxFFile::Eof}\label{wxffileeof}

\constfunc{bool}{Eof}{\void}

Returns TRUE if the an attempt has been made to read {\it past}
the end of the file. 

Note that the behaviour of the file descriptor based class
\helpref{wxFile}{wxfile} is different as \helpref{wxFile::Eof}{wxfileeof}
will return TRUE here as soon as the last byte of the file has been
read.

\membersection{wxFFile::Flush}\label{wxffileflush}

\func{bool}{Flush}{\void}

Flushes the file and returns TRUE on success.

\membersection{wxFFile::IsOpened}\label{wxffileisopened}

\constfunc{bool}{IsOpened}{\void}

Returns TRUE if the file has been opened.

\membersection{wxFFile::Length}\label{wxffilelength}

\constfunc{size\_t}{Length}{\void}

Returns the length of the file.

\membersection{wxFFile::Open}\label{wxffileopen}

\func{bool}{Open}{\param{const char*}{ filename}, \param{const char*}{ mode = "r"}}

Opens the file, returning TRUE if successful.

\wxheading{Parameters}

\docparam{filename}{The filename.}

\docparam{mode}{The mode in which to open the file.}

\membersection{wxFFile::Read}\label{wxffileread}

\func{size\_t}{Read}{\param{void*}{ buffer}, \param{off\_t}{ count}}

Reads the specified number of bytes into a buffer, returning the actual number read.

\wxheading{Parameters}

\docparam{buffer}{A buffer to receive the data.}

\docparam{count}{The number of bytes to read.}

\wxheading{Return value}

The number of bytes read.

\membersection{wxFFile::Seek}\label{wxffileseek}

\func{bool}{Seek}{\param{long }{ofs}, \param{wxSeekMode }{mode = wxFromStart}}

Seeks to the specified position and returs TRUE on success.

\wxheading{Parameters}

\docparam{ofs}{Offset to seek to.}

\docparam{mode}{One of {\bf wxFromStart}, {\bf wxFromEnd}, {\bf wxFromCurrent}.}

\membersection{wxFFile::SeekEnd}\label{wxffileseekend}

\func{bool}{SeekEnd}{\param{long }{ofs = 0}}

Moves the file pointer to the specified number of bytes before the end of the file
and returns TRUE on success.

\wxheading{Parameters}

\docparam{ofs}{Number of bytes before the end of the file.}

\membersection{wxFFile::Tell}\label{wxffiletell}

\constfunc{size\_t}{Tell}{\void}

Returns the current position.

\membersection{wxFFile::Write}\label{wxffilewrite}

\func{size\_t}{Write}{\param{const void*}{ buffer}, \param{size\_t}{ count}}

Writes the specified number of bytes from a buffer.

\wxheading{Parameters}

\docparam{buffer}{A buffer containing the data.}

\docparam{count}{The number of bytes to write.}

\wxheading{Return value}

Number of bytes written.

\membersection{wxFFile::Write}\label{wxffilewrites}

\func{bool}{Write}{\param{const wxString\& }{s}, \param{wxMBConv\&}{ conv = wxConvLibc}}

Writes the contents of the string to the file, returns TRUE on success.

The second argument is only meaningful in Unicode build of wxWindows when
{\it conv} is used to convert {\it s} to multibyte representation.