docs/latex/wx/textfile.tex

   1 \section{\class{wxTextFile}}\label{wxtextfile}
   2
   3 The wxTextFile is a simple class which allows to work with text files on line by
   4 line basis. It also understands the differences in line termination characters
   5 under different platforms and will not do anything bad to files with "non
   6 native" line termination sequences - in fact, it can be also used to modify the
   7 text files and change the line termination characters from one type (say DOS) to
   8 another (say Unix).
   9
  10 One word of warning: the class is not at all optimized for big files and so it
  11 will load the file entirely into memory when opened. Of course, you should not
  12 work in this way with large files (as an estimation, anything over 1 Megabyte is
  13 surely too big for this class). On the other hand, it is not a serious
  14 limitation for the small files like configuration files or programs sources
  15 which are well handled by wxTextFile.
  16
  17 The typical things you may do with wxTextFile in order are:
  18
  19 \begin{itemize}\itemsep=0pt
  20 \item Create and open it: this is done with \helpref{Open}{wxtextfileopen}
  21 function which opens the file (name may be specified either as Open argument or
  22 in the constructor), reads its contents in memory and closes it. If all of these
  23 operations are successful, Open() will return TRUE and FALSE on error.
  24 \item Work with the lines in the file: this may be done either with "direct
  25 access" functions like \helpref{GetLineCount}{wxtextfilegetlinecount} and
  26 \helpref{GetLine}{wxtextfilegetline} ({\it operator[]} does exactly the same
  27 but looks more like array addressing) or with "sequential access" functions
  28 which include \helpref{GetFirstLine}{wxtextfilegetfirstline}/
  29 \helpref{GetNextLine}{wxtextfilegetnextline} and also
  30 \helpref{GetLastLine}{wxtextfilegetlastline}/\helpref{GetPrevLine}{wxtextfilegetprevline}.
  31 For the sequential access functions the current line number is maintained: it is
  32 returned by \helpref{GetCurrentLine}{wxtextfilegetcurrentline} and may be
  33 changed with \helpref{GoToLine}{wxtextfilegotoline}.
  34 \item Add/remove lines to the file: \helpref{AddLine}{wxtextfileaddline} and
  35 \helpref{InsertLine}{wxtextfileinsertline} add new lines while
  36 \helpref{RemoveLine}{wxtextfileremoveline} deletes the existing ones.
  37 \item Save your changes: notice that the changes you make to the file will {\bf
  38 not} be saved automatically; calling \helpref{Close}{wxtextfileclose} or doing
  39 nothing discards them! To save the changes you must explicitly call
  40 \helpref{Write}{wxtextfilewrite} - here, you may also change the line
  41 termination type if you wish.
  42 \end{itemize}
  43
  44 \wxheading{Derived from}
  45
  46 No base class
  47
  48 \wxheading{Include files}
  49
  50 <wx/textfile.h>
  51
  52 \wxheading{Data structures}
  53
  54 The following constants identify the line termination type:
  55 \begin{verbatim}
  56 enum wxTextFileType
  57 {
  58     wxTextFileType_None,  // incomplete (the last line of the file only)
  59     wxTextFileType_Unix,  // line is terminated with 'LF' = 0xA = 10 = '\n'
  60     wxTextFileType_Dos,   //                         'CR' 'LF'
  61     wxTextFileType_Mac    //                         'CR' = 0xD = 13 = '\r'
  62 };
  63 \end{verbatim}
  64
  65 \wxheading{See also}
  66
  67 \helpref{wxFile}{wxfile}
  68
  69 \latexignore{\rtfignore{\wxheading{Members}}}
  70
  71 \membersection{wxTextFile::wxTextFile}\label{wxtextfilectordef}
  72
  73 \constfunc{}{wxTextFile}{\void}
  74
  75 Default constructor, use Open(string) to initialize the object.
  76
  77 \membersection{wxTextFile::wxTextFile}\label{wxtextfilector}
  78
  79 \constfunc{}{wxTextFile}{\param{const wxString\& }{strFile}}
  80
  81 Constructor does not load the file into memory, use Open() to do it.
  82
  83 \membersection{wxTextFile::Exists}\label{wxtextfileexists}
  84
  85 \constfunc{bool}{Exists}{\void}
  86
  87 Return TRUE if file exists - the name of the file should have been specified
  88 in the constructor before calling Exists().
  89
  90 \membersection{wxTextFile::Open}\label{wxtextfileopen}
  91
  92 \constfunc{bool}{Open}{\void}
  93
  94 Open() opens the file with the name which was given in the \helpref{constructor}{wxtextfilector}
  95 and also loads file in memory on success.
  96
  97 \membersection{wxTextFile::Open}\label{wxtextfileopenname}
  98
  99 \constfunc{bool}{Open}{\param{const wxString\& }{strFile}}
 100
 101 Same as \helpref{Open()}{wxtextfileopen} but allows to specify the file name
 102 (must be used if the default constructor was used to create the object).
 103
 104 \membersection{wxTextFile::Close}\label{wxtextfileclose}
 105
 106 \constfunc{bool}{Close}{\void}
 107
 108 Closes the file and frees memory, {\bf losing all changes}. Use \helpref{Write()}{wxtextfilewrite}
 109 if you want to save them.
 110
 111 \membersection{wxTextFile::IsOpened}\label{wxtextfileisopened}
 112
 113 \constfunc{bool}{IsOpened}{\void}
 114
 115 Returns TRUE if the file is currently opened.
 116
 117 \membersection{wxTextFile::GetLineCount}\label{wxtextfilegetlinecount}
 118
 119 \constfunc{size\_t}{GetLineCount}{\void}
 120
 121 Get the number of lines in the file.
 122
 123 \membersection{wxTextFile::GetLine}\label{wxtextfilegetline}
 124
 125 \constfunc{wxString\&}{GetLine}{\param{size\_t }{n}}
 126
 127 Retrieves the line number {\it n} from the file. The returned line may be
 128 modified but you shouldn't add line terminator at the end - this will be done
 129 by wxTextFile.
 130
 131 \membersection{wxTextFile::operator[]}\label{wxtextfileoperatorarray}
 132
 133 \constfunc{wxString\&}{operator[]}{\param{size\_t }{n}}
 134
 135 The same as \helpref{GetLine}{wxtextfilegetline}.
 136
 137 \membersection{wxTextFile::GetCurrentLine}\label{wxtextfilegetcurrentline}
 138
 139 \constfunc{size\_t}{GetCurrentLine}{\void}
 140
 141 Returns the current line: it has meaning only when you're using
 142 GetFirstLine()/GetNextLine() functions, it doesn't get updated when
 143 you're using "direct access" functions like GetLine(). GetFirstLine() and
 144 GetLastLine() also change the value of the current line, as well as
 145 GoToLine().
 146
 147 \membersection{wxTextFile::GoToLine}\label{wxtextfilegotoline}
 148
 149 \constfunc{void}{GoToLine}{\param{size\_t }{n}}
 150
 151 Changes the value returned by \helpref{GetCurrentLine}{wxtextfilegetcurrentline}
 152 and used by \helpref{GetFirstLine()}{wxtextfilegetfirstline}/\helpref{GetNextLine()}{wxtextfilegetnextline}.
 153
 154 \membersection{wxTextFile::Eof}\label{wxtextfileeof}
 155
 156 \constfunc{bool}{Eof}{\void}
 157
 158 Returns TRUE if the current line is the last one.
 159
 160 \membersection{wxTextFile::GetFirstLine}\label{wxtextfilegetfirstline}
 161
 162 \constfunc{wxString\&}{GetFirstLine}{\void}
 163
 164 This method together with \helpref{GetNextLine()}{wxtextfilegetnextline}
 165 allows more "iterator-like" traversal of the list of lines, i.e. you may
 166 write something like:
 167
 168 \begin{verbatim}
 169 for ( str = GetFirstLine(); !Eof(); str = GetNextLine() )
 170 {
 171     // do something with the current line in str
 172 }
 173 \end{verbatim}
 174
 175 \membersection{wxTextFile::GetNextLine}\label{wxtextfilegetnextline}
 176
 177 \func{wxString\&}{GetNextLine}{\void}
 178
 179 Gets the next line (see \helpref{GetFirstLine}{wxtextfilegetfirstline} for
 180 the example).
 181
 182 \membersection{wxTextFile::GetPrevLine}\label{wxtextfilegetprevline}
 183
 184 \func{wxString\&}{GetPrevLine}{\void}
 185
 186 Gets the previous line in the file.
 187
 188 \membersection{wxTextFile::GetLastLine}\label{wxtextfilegetlastline}
 189
 190 \func{wxString\&}{GetLastLine}{\void}
 191
 192 Gets the last line of the file.
 193
 194 \membersection{wxTextFile::GetLineType}\label{wxtextfilegetlinetype}
 195
 196 \constfunc{wxTextFileType}{GetLineType}{\param{size\_t }{n}}
 197
 198 Get the type of the line (see also \helpref{GetEOL}{wxtextfilegeteol})
 199
 200 \membersection{wxTextFile::GuessType}\label{wxtextfileguesstype}
 201
 202 \constfunc{wxTextFileType}{GuessType}{\void}
 203
 204 Guess the type of file (which is supposed to be opened). If sufficiently
 205 many lines of the file are in DOS/Unix/Mac format, the corresponding value will
 206 be returned. If the detection mechanism fails wxTextFileType\_None is returned.
 207
 208 \membersection{wxTextFile::GetName}\label{wxtextfilegetname}
 209
 210 \constfunc{const char*}{GetName}{\void}
 211
 212 Get the name of the file.
 213
 214 \membersection{wxTextFile::AddLine}\label{wxtextfileaddline}
 215
 216 \constfunc{void}{AddLine}{\param{const wxString\& }{str}, \param{wxTextFileType }{type = typeDefault}}
 217
 218 Adds a line to the end of file.
 219
 220 \membersection{wxTextFile::InsertLine}\label{wxtextfileinsertline}
 221
 222 \constfunc{void}{InsertLine}{\param{const wxString\& }{str}, \param{size\_t }{n}, \param{wxTextFileType }{type = typeDefault}}
 223
 224 Insert a line before the line number {\it n}.
 225
 226 \membersection{wxTextFile::RemoveLine}\label{wxtextfileremoveline}
 227
 228 \constfunc{void}{RemoveLine}{\param{size\_t }{n}}
 229
 230 Delete line number {\it n} from the file.
 231
 232 \membersection{wxTextFile::Write}\label{wxtextfilewrite}
 233
 234 \constfunc{bool}{Write}{\param{wxTextFileType }{typeNew = wxTextFileType\_None}}
 235
 236 Change the file on disk. The {\it typeNew} parameter allows you to change the
 237 file format (default argument means "don't change type") and may be used to
 238 convert, for example, DOS files to Unix.
 239
 240 Returns TRUE if operation succeeded, FALSE if it failed.
 241
 242 \membersection{wxTextFile::GetEOL}\label{wxtextfilegeteol}
 243
 244 \constfunc{static const char*}{GetEOL}{\param{wxTextFileType }{type = typeDefault}}
 245
 246 Get the line termination string corresponding to given constant. {\it typeDefault} is
 247 the value defined during the compilation and corresponds to the native format of the
 248 platform, i.e. it will be wxTextFileType\_Dos under Windows, wxTextFileType\_Unix under
 249 Unix and wxTextFileType\_Mac under Mac.
 250
 251 \membersection{wxTextFile::\destruct{wxTextFile}}\label{wxtextfiledtor}
 252
 253 \constfunc{}{\destruct{wxTextFile}}{\void}
 254
 255 Destructor does nothing.
 256