e694c22c31
2. dir.h/.cpp added to the makefiles git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@4877 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
469 lines
14 KiB
TeX
469 lines
14 KiB
TeX
\section{\class{wxFile}}\label{wxfile}
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A wxFile performs raw file I/O. This is a very small class designed to
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minimize the overhead of using it - in fact, there is hardly any overhead at
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all, but using it brings you automatic error checking and hides differences
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between platforms and compilers. wxFile also automatically closes the file in
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its destructor making it unnecessary to worry about forgetting to do it.
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\wxheading{Derived from}
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None.
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\wxheading{Include files}
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<wx/file.h>
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\wxheading{Constants}
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wx/file.h defines the following constants:
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{\small
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\begin{verbatim}
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#define wxS_IRUSR 00400
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#define wxS_IWUSR 00200
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#define wxS_IXUSR 00100
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#define wxS_IRGRP 00040
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#define wxS_IWGRP 00020
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#define wxS_IXGRP 00010
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#define wxS_IROTH 00004
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#define wxS_IWOTH 00002
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#define wxS_IXOTH 00001
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// default mode for the new files: corresponds to umask 022
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#define wxS_DEFAULT (wxS_IRUSR | wxS_IWUSR | wxS_IRGRP | wxS_IWGRP | wxS_IROTH | wxS_IWOTH)
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\end{verbatim}
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}
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These constants define the file access rights and are used with
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\helpref{wxFile::Create}{wxfilecreate} and \helpref{wxFile::Open}{wxfileopen}.
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The {\it OpenMode} enumeration defines the different modes for opening a file,
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it's defined inside wxFile class so its members should be specified with {\it wxFile::} scope
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resolution prefix. It is also used with \helpref{wxFile::Access}{wxfileaccess} function.
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\twocolwidtha{7cm}
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\begin{twocollist}\itemsep=0pt%
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\twocolitem{{\bf wxFile::read}}{Open file for reading or test if it can be opened for reading with Access()}
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\twocolitem{{\bf wxFile::write}}{Open file for writing deleting the contents of the file if it already exists
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or test if it can be opened for writing with Access()}
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\twocolitem{{\bf wxFile::read\_write}}{Open file for reading and writing; can not be used with Access()}
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\twocolitem{{\bf wxFile::write\_append}}{Open file for appending: the file is opened for writing, but the old
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contents of the file is not erased and the file pointer is initially placed at the end of the file;
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can not be used with Access()}
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\end{twocollist}
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Other constants defined elsewhere but used by wxFile functions are wxInvalidOffset which represents an
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invalid value of type {\it off\_t} and is returned by functions returning {\it off\_t} on error and the seek
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mode constants used with \helpref{Seek()}{wxfileseek}:
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\twocolwidtha{7cm}
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\begin{twocollist}\itemsep=0pt%
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\twocolitem{{\bf wxFromStart}}{Count offset from the start of the file}
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\twocolitem{{\bf wxFromCurrent}}{Count offset from the current position of the file pointer}
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\twocolitem{{\bf wxFromEnd}}{Count offset from the end of the file (backwards)}
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\end{twocollist}
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\latexignore{\rtfignore{\wxheading{Members}}}
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\membersection{wxFile::wxFile}\label{wxfileconstr}
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\func{}{wxFile}{\void}
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Default constructor.
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\func{}{wxFile}{\param{const char*}{ filename}, \param{wxFile::OpenMode}{ mode = wxFile::read}}
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Opens a file with the given mode. As there is no way to return whether the
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operation was successful or not from the constructor you should test the
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return value of \helpref{IsOpened}{wxfileisopened} to check that it didn't
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fail.
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\func{}{wxFile}{\param{int}{ fd}}
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Associates the file with the given file descriptor, which has already been opened.
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\wxheading{Parameters}
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\docparam{filename}{The filename.}
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\docparam{mode}{The mode in which to open the file. May be one of {\bf wxFile::read}, {\bf wxFile::write} and {\bf wxFile::read\_write}.}
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\docparam{fd}{An existing file descriptor (see \helpref{Attach()}{wxfileattach} for the list of predefined descriptors)}
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\membersection{wxFile::\destruct{wxFile}}
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\func{}{\destruct{wxFile}}{\void}
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Destructor will close the file.
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NB: it is not virtual so you should use wxFile polymorphically.
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\membersection{wxFile::Access}\label{wxfileaccess}
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\func{static bool}{Access}{\param{const char *}{ name}, \param{OpenMode}{ mode}}
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This function verifies if we may access the given file in specified mode. Only
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values of wxFile::read or wxFile::write really make sense here.
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\membersection{wxFile::Attach}\label{wxfileattach}
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\func{void}{Attach}{\param{int}{ fd}}
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Attaches an existing file descriptor to the wxFile object. Example of predefined
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file descriptors are 0, 1 and 2 which correspond to stdin, stdout and stderr (and
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have symbolic names of wxFile::fd\_stdin, wxFile::fd\_stdout and wxFile::fd\_stderr).
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The descriptor should be already opened and it will be closed by wxFile
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object.
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\membersection{wxFile::Close}\label{wxfileclose}
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\func{void}{Close}{\void}
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Closes the file.
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\membersection{wxFile::Create}\label{wxfilecreate}
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\func{bool}{Create}{\param{const char*}{ filename}, \param{bool}{ overwrite = FALSE}, \param{int }{access = wxS\_DEFAULT}}
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Creates a file for writing. If the file already exists, setting {\bf overwrite} to TRUE
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will ensure it is overwritten.
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\membersection{wxFile::Detach}\label{wxfiledetach}
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\func{void}{Detach}{\void}
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Get back a file descriptor from wxFile object - the caller is responsible for closing the file if this
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descriptor is opened. \helpref{IsOpened()}{wxfileisopened} will return FALSE after call to Detach().
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\membersection{wxFile::fd}\label{wxfilefd}
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\constfunc{int}{fd}{\void}
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Returns the file descriptor associated with the file.
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\membersection{wxFile::Eof}\label{wxfileeof}
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\constfunc{bool}{Eof}{\void}
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Returns TRUE if the end of the file has been reached (the last byte has been read).
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Note that the behaviour of the file pointer based class
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\helpref{wxFFile}{wxffile} is different as \helpref{wxFFile::Eof}{wxffileeof}
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will return TRUE here only if an attempt has been made to read
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{\it past} the last byte of the file.
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\membersection{wxFile::Exists}\label{wxfileexists}
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\func{static bool}{Exists}{\param{const char*}{ filename}}
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Returns TRUE if the given name specifies an existing regular file (not a
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directory or a link)
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\membersection{wxFile::Flush}\label{wxfileflush}
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\func{bool}{Flush}{\void}
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Flushes the file descriptor.
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Note that wxFile::Flush is not implemented on some Windows compilers
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due to a missing fsync function, which reduces the usefulness of this function
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(it can still be called but it will do nothing on unsupported compilers).
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\membersection{wxFile::IsOpened}\label{wxfileisopened}
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\constfunc{bool}{IsOpened}{\void}
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Returns TRUE if the file has been opened.
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\membersection{wxFile::Length}\label{wxfilelength}
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\constfunc{off\_t}{Length}{\void}
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Returns the length of the file.
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\membersection{wxFile::Open}\label{wxfileopen}
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\func{bool}{Open}{\param{const char*}{ filename}, \param{wxFile::OpenMode}{ mode = wxFile::read}}
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Opens the file, returning TRUE if successful.
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\wxheading{Parameters}
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\docparam{filename}{The filename.}
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\docparam{mode}{The mode in which to open the file. May be one of {\bf wxFile::read}, {\bf wxFile::write} and {\bf wxFile::read\_write}.}
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\membersection{wxFile::Read}\label{wxfileread}
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\func{off\_t}{Read}{\param{void*}{ buffer}, \param{off\_t}{ count}}
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Reads the specified number of bytes into a buffer, returning the actual number read.
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\wxheading{Parameters}
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\docparam{buffer}{A buffer to receive the data.}
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\docparam{count}{The number of bytes to read.}
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\wxheading{Return value}
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The number of bytes read, or the symbol {\bf wxInvalidOffset} (-1) if there was an error.
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\membersection{wxFile::Seek}\label{wxfileseek}
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\func{off\_t}{Seek}{\param{off\_t }{ofs}, \param{wxSeekMode }{mode = wxFromStart}}
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Seeks to the specified position.
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\wxheading{Parameters}
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\docparam{ofs}{Offset to seek to.}
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\docparam{mode}{One of {\bf wxFromStart}, {\bf wxFromEnd}, {\bf wxFromCurrent}.}
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\wxheading{Return value}
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The actual offset position achieved, or wxInvalidOffset on failure.
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\membersection{wxFile::SeekEnd}\label{wxfileseekend}
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\func{off\_t}{SeekEnd}{\param{off\_t }{ofs = 0}}
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Moves the file pointer to the specified number of bytes before the end of the file.
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\wxheading{Parameters}
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\docparam{ofs}{Number of bytes before the end of the file.}
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\wxheading{Return value}
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The actual offset position achieved, or wxInvalidOffset on failure.
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\membersection{wxFile::Tell}\label{wxfiletell}
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\constfunc{off\_t}{Tell}{\void}
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Returns the current position or wxInvalidOffset if file is not opened or if another
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error occured.
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\membersection{wxFile::Write}\label{wxfilewrite}
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\func{bool}{Write}{\param{const void*}{ buffer}, \param{off\_t}{ count}}
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Writes the specified number of bytes from a buffer.
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\wxheading{Parameters}
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\docparam{buffer}{A buffer containing the data.}
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\docparam{count}{The number of bytes to write.}
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\wxheading{Return value}
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TRUE if the operation was successful.
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\membersection{wxFile::Write}\label{wxfilewrites}
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\func{bool}{Write}{\param{const wxString\& }{s}}
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Writes the contents of the string to the file, returns TRUE on success.
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\section{\class{wxFFile}}\label{wxffile}
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A wxFFile performs raw file I/O. This is a very small class designed to
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minimize the overhead of using it - in fact, there is hardly any overhead at
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all, but using it brings you automatic error checking and hides differences
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between platforms and compilers.
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\wxheading{Derived from}
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None.
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\wxheading{Include files}
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<wx/ffile.h>
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\twocolwidtha{7cm}
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\begin{twocollist}\itemsep=0pt%
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\twocolitem{{\bf wxFromStart}}{Count offset from the start of the file}
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\twocolitem{{\bf wxFromCurrent}}{Count offset from the current position of the file pointer}
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\twocolitem{{\bf wxFromEnd}}{Count offset from the end of the file (backwards)}
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\end{twocollist}
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\latexignore{\rtfignore{\wxheading{Members}}}
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\membersection{wxFFile::wxFFile}\label{wxffileconstr}
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\func{}{wxFFile}{\void}
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Default constructor.
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\func{}{wxFFile}{\param{const char*}{ filename}, \param{const char*}{ mode = "r"}}
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Opens a file with the given mode. As there is no way to return whether the
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operation was successful or not from the constructor you should test the
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return value of \helpref{IsOpened}{wxffileisopened} to check that it didn't
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fail.
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\func{}{wxFFile}{\param{FILE*}{ fp}}
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Opens a file with the given file pointer, which has already been opened.
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\wxheading{Parameters}
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\docparam{filename}{The filename.}
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\docparam{mode}{The mode in which to open the file using standard C strings.}
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\docparam{fp}{An existing file descriptor, such as stderr.}
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\membersection{wxFFile::\destruct{wxFFile}}
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\func{}{\destruct{wxFFile}}{\void}
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Destructor will close the file.
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NB: it is not virtual so you should {\it not} derive from wxFFile!
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\membersection{wxFFile::Attach}\label{wxffileattach}
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\func{void}{Attach}{\param{FILE*}{ fp}}
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Attaches an existing file pointer to the wxFFile object.
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The descriptor should be already opened and it will be closed by wxFFile
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object.
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\membersection{wxFFile::Close}\label{wxffileclose}
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\func{bool}{Close}{\void}
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Closes the file and returns TRUE on success.
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\membersection{wxFFile::Detach}\label{wxffiledetach}
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\func{void}{Detach}{\void}
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Get back a file pointer from wxFFile object - the caller is responsible for closing the file if this
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descriptor is opened. \helpref{IsOpened()}{wxffileisopened} will return FALSE after call to Detach().
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\membersection{wxFFile::fp}\label{wxffilefp}
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\constfunc{FILE *}{fp}{\void}
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Returns the file pointer associated with the file.
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\membersection{wxFFile::Eof}\label{wxffileeof}
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\constfunc{bool}{Eof}{\void}
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Returns TRUE if the an attempt has been made to read {\it past}
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the end of the file.
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Note that the behaviour of the file descriptor based class
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\helpref{wxFile}{wxfile} is different as \helpref{wxFile::Eof}{wxfileeof}
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will return TRUE here as soon as the last byte of the file has been
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read.
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\membersection{wxFFile::Flush}\label{wxffileflush}
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\func{bool}{Flush}{\void}
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Flushes the file and returns TRUE on success.
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\membersection{wxFFile::IsOpened}\label{wxffileisopened}
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\constfunc{bool}{IsOpened}{\void}
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Returns TRUE if the file has been opened.
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\membersection{wxFFile::Length}\label{wxffilelength}
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\constfunc{size\_t}{Length}{\void}
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Returns the length of the file.
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\membersection{wxFFile::Open}\label{wxffileopen}
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\func{bool}{Open}{\param{const char*}{ filename}, \param{const char*}{ mode = "r"}}
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Opens the file, returning TRUE if successful.
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\wxheading{Parameters}
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\docparam{filename}{The filename.}
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\docparam{mode}{The mode in which to open the file.}
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\membersection{wxFFile::Read}\label{wxffileread}
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\func{size\_t}{Read}{\param{void*}{ buffer}, \param{off\_t}{ count}}
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Reads the specified number of bytes into a buffer, returning the actual number read.
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\wxheading{Parameters}
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\docparam{buffer}{A buffer to receive the data.}
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\docparam{count}{The number of bytes to read.}
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\wxheading{Return value}
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The number of bytes read.
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\membersection{wxFFile::Seek}\label{wxffileseek}
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\func{bool}{Seek}{\param{long }{ofs}, \param{wxSeekMode }{mode = wxFromStart}}
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Seeks to the specified position and returs TRUE on success.
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\wxheading{Parameters}
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\docparam{ofs}{Offset to seek to.}
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\docparam{mode}{One of {\bf wxFromStart}, {\bf wxFromEnd}, {\bf wxFromCurrent}.}
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\membersection{wxFFile::SeekEnd}\label{wxffileseekend}
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\func{bool}{SeekEnd}{\param{long }{ofs = 0}}
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Moves the file pointer to the specified number of bytes before the end of the file
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and returns TRUE on success.
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\wxheading{Parameters}
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\docparam{ofs}{Number of bytes before the end of the file.}
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\membersection{wxFFile::Tell}\label{wxffiletell}
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\constfunc{size\_t}{Tell}{\void}
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Returns the current position.
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\membersection{wxFFile::Write}\label{wxffilewrite}
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\func{size_t}{Write}{\param{const void*}{ buffer}, \param{size\_t}{ count}}
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Writes the specified number of bytes from a buffer.
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\wxheading{Parameters}
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\docparam{buffer}{A buffer containing the data.}
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\docparam{count}{The number of bytes to write.}
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\wxheading{Return value}
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Number of bytes written.
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\membersection{wxFFile::Write}\label{wxffilewrites}
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\func{bool}{Write}{\param{const wxString\& }{s}}
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Writes the contents of the string to the file, returns TRUE on success.
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