docs/latex/wx/ffile.tex

   1 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
   2 %% Name:        ffile.tex
   3 %% Purpose:     wxFFile documentation
   4 %% Author:      Vadim Zeitlin
   5 %% Modified by:
   6 %% Created:     14.01.02 (extracted from file.tex)
   7 %% RCS-ID:      $Id$
   8 %% Copyright:   (c) Vadim Zeitlin
   9 %% License:     wxWidgets license
  10 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  11
  12 \section{\class{wxFFile}}\label{wxffile}
  13
  14 wxFFile implements buffered file I/O. This is a very small class designed to
  15 minimize the overhead of using it - in fact, there is hardly any overhead at
  16 all, but using it brings you automatic error checking and hides differences
  17 between platforms and compilers. It wraps inside it a {\tt FILE *} handle used
  18 by standard C IO library (also known as {\tt stdio}).
  19
  20 \wxheading{Derived from}
  21
  22 None.
  23
  24 \wxheading{Include files}
  25
  26 <wx/ffile.h>
  27
  28 \twocolwidtha{7cm}
  29 \begin{twocollist}\itemsep=0pt%
  30 \twocolitem{{\bf wxFromStart}}{Count offset from the start of the file}
  31 \twocolitem{{\bf wxFromCurrent}}{Count offset from the current position of the file pointer}
  32 \twocolitem{{\bf wxFromEnd}}{Count offset from the end of the file (backwards)}
  33 \end{twocollist}
  34
  35 \latexignore{\rtfignore{\wxheading{Members}}}
  36
  37
  38 \membersection{wxFFile::wxFFile}\label{wxffilector}
  39
  40 \func{}{wxFFile}{\void}
  41
  42 Default constructor.
  43
  44 \func{}{wxFFile}{\param{const char*}{ filename}, \param{const char*}{ mode = "r"}}
  45
  46 Opens a file with the given mode. As there is no way to return whether the
  47 operation was successful or not from the constructor you should test the
  48 return value of \helpref{IsOpened}{wxffileisopened} to check that it didn't
  49 fail.
  50
  51 \func{}{wxFFile}{\param{FILE*}{ fp}}
  52
  53 Opens a file with the given file pointer, which has already been opened.
  54
  55 \wxheading{Parameters}
  56
  57 \docparam{filename}{The filename.}
  58
  59 \docparam{mode}{The mode in which to open the file using standard C strings.
  60 Note that you should use {\tt "b"} flag if you use binary files under Windows
  61 or the results might be unexpected due to automatic newline conversion done
  62 for the text files.}
  63
  64 \docparam{fp}{An existing file descriptor, such as stderr.}
  65
  66
  67 \membersection{wxFFile::\destruct{wxFFile}}\label{wxffiledtor}
  68
  69 \func{}{\destruct{wxFFile}}{\void}
  70
  71 Destructor will close the file.
  72
  73 NB: it is not virtual so you should {\it not} derive from wxFFile!
  74
  75
  76 \membersection{wxFFile::Attach}\label{wxffileattach}
  77
  78 \func{void}{Attach}{\param{FILE*}{ fp}}
  79
  80 Attaches an existing file pointer to the wxFFile object.
  81
  82 The descriptor should be already opened and it will be closed by wxFFile
  83 object.
  84
  85
  86 \membersection{wxFFile::Close}\label{wxffileclose}
  87
  88 \func{bool}{Close}{\void}
  89
  90 Closes the file and returns \true on success.
  91
  92
  93 \membersection{wxFFile::Detach}\label{wxffiledetach}
  94
  95 \func{void}{Detach}{\void}
  96
  97 Get back a file pointer from wxFFile object -- the caller is responsible for closing the file if this
  98 descriptor is opened. \helpref{IsOpened()}{wxffileisopened} will return \false after call to Detach().
  99
 100
 101 \membersection{wxFFile::fp}\label{wxffilefp}
 102
 103 \constfunc{FILE *}{fp}{\void}
 104
 105 Returns the file pointer associated with the file.
 106
 107
 108 \membersection{wxFFile::Eof}\label{wxffileeof}
 109
 110 \constfunc{bool}{Eof}{\void}
 111
 112 Returns \true if the an attempt has been made to read {\it past}
 113 the end of the file.
 114
 115 Note that the behaviour of the file descriptor based class
 116 \helpref{wxFile}{wxfile} is different as \helpref{wxFile::Eof}{wxfileeof}
 117 will return \true here as soon as the last byte of the file has been
 118 read.
 119
 120 Also note that this method may only be called for opened files and may crash if
 121 the file is not opened.
 122
 123 \wxheading{See also}
 124
 125 \helpref{IsOpened}{wxffileisopened}
 126
 127
 128 \membersection{wxFFile::Error}\label{wxffileerror}
 129
 130 Returns \true if an error has occured on this file, similar to the standard
 131 \texttt{ferror()} function.
 132
 133 Please note that this method may only be called for opened files and may crash
 134 if the file is not opened.
 135
 136 \wxheading{See also}
 137
 138 \helpref{IsOpened}{wxffileisopened}
 139
 140
 141 \membersection{wxFFile::Flush}\label{wxffileflush}
 142
 143 \func{bool}{Flush}{\void}
 144
 145 Flushes the file and returns \true on success.
 146
 147
 148 \membersection{wxFFile::GetKind}\label{wxffilegetfilekind}
 149
 150 \constfunc{wxFileKind}{GetKind}{\void}
 151
 152 Returns the type of the file. Possible return values are:
 153
 154 \begin{verbatim}
 155 enum wxFileKind
 156 {
 157   wxFILE_KIND_UNKNOWN,
 158   wxFILE_KIND_DISK,     // a file supporting seeking to arbitrary offsets
 159   wxFILE_KIND_TERMINAL, // a tty
 160   wxFILE_KIND_PIPE      // a pipe
 161 };
 162
 163 \end{verbatim}
 164
 165
 166 \membersection{wxFFile::IsOpened}\label{wxffileisopened}
 167
 168 \constfunc{bool}{IsOpened}{\void}
 169
 170 Returns \true if the file is opened. Most of the methods of this class may only
 171 be used for an opened file.
 172
 173
 174 \membersection{wxFFile::Length}\label{wxffilelength}
 175
 176 \constfunc{wxFileOffset}{Length}{\void}
 177
 178 Returns the length of the file.
 179
 180
 181 \membersection{wxFFile::Open}\label{wxffileopen}
 182
 183 \func{bool}{Open}{\param{const char*}{ filename}, \param{const char*}{ mode = "r"}}
 184
 185 Opens the file, returning \true if successful.
 186
 187 \wxheading{Parameters}
 188
 189 \docparam{filename}{The filename.}
 190
 191 \docparam{mode}{The mode in which to open the file.}
 192
 193
 194 \membersection{wxFFile::Read}\label{wxffileread}
 195
 196 \func{size\_t}{Read}{\param{void*}{ buffer}, \param{size\_t}{ count}}
 197
 198 Reads the specified number of bytes into a buffer, returning the actual number read.
 199
 200 \wxheading{Parameters}
 201
 202 \docparam{buffer}{A buffer to receive the data.}
 203
 204 \docparam{count}{The number of bytes to read.}
 205
 206 \wxheading{Return value}
 207
 208 The number of bytes read.
 209
 210
 211 \membersection{wxFFile::Seek}\label{wxffileseek}
 212
 213 \func{bool}{Seek}{\param{wxFileOffset }{ofs}, \param{wxSeekMode }{mode = wxFromStart}}
 214
 215 Seeks to the specified position and returns \true on success.
 216
 217 \wxheading{Parameters}
 218
 219 \docparam{ofs}{Offset to seek to.}
 220
 221 \docparam{mode}{One of {\bf wxFromStart}, {\bf wxFromEnd}, {\bf wxFromCurrent}.}
 222
 223
 224 \membersection{wxFFile::SeekEnd}\label{wxffileseekend}
 225
 226 \func{bool}{SeekEnd}{\param{wxFileOffset }{ofs = 0}}
 227
 228 Moves the file pointer to the specified number of bytes before the end of the file
 229 and returns \true on success.
 230
 231 \wxheading{Parameters}
 232
 233 \docparam{ofs}{Number of bytes before the end of the file.}
 234
 235
 236 \membersection{wxFFile::Tell}\label{wxffiletell}
 237
 238 \constfunc{wxFileOffset}{Tell}{\void}
 239
 240 Returns the current position.
 241
 242
 243 \membersection{wxFFile::Write}\label{wxffilewrite}
 244
 245 \func{size\_t}{Write}{\param{const void*}{ buffer}, \param{size\_t}{ count}}
 246
 247 Writes the specified number of bytes from a buffer.
 248
 249 \wxheading{Parameters}
 250
 251 \docparam{buffer}{A buffer containing the data.}
 252
 253 \docparam{count}{The number of bytes to write.}
 254
 255 \wxheading{Return value}
 256
 257 Number of bytes written.
 258
 259
 260 \membersection{wxFFile::Write}\label{wxffilewrites}
 261
 262 \func{bool}{Write}{\param{const wxString\& }{s}, \param{wxMBConv\&}{ conv = wxConvUTF8}}
 263
 264 Writes the contents of the string to the file, returns \true on success.
 265
 266 The second argument is only meaningful in Unicode build of wxWidgets when
 267 {\it conv} is used to convert {\it s} to multibyte representation.
 268
 269