TFile - Binary File I/O

Source: source/classes/tfile.prg

TFile provides low-level binary file input/output operations. It wraps the Harbour file-handling APIs (FOpen(), FRead(), FWrite(), etc.) into an object-oriented interface with sequential and random-access positioning, byte/word/string read/write, searching, counting, and insertion/deletion of bytes. TFile is the base parent class of TObjFile, TLibFile, and TTxtFile.

classDiagram class TFile { +cName +hFile +nLen +nMode +New(cFile, nMode) +Create(cFile, nMode) +nGetByte() +nGetWord() +cGetStr(n) +PutByte(n) +PutWord(n) +PutStr(c) +GoTop() +GoBottom() +Skip(n) +GoTo(n) +Seek(cStr) +Count(cStr) +DelBytes(n) +InsBytes(n) +lEof() +lBoF() +Close() } TFile <|-- TObjFile TFile <|-- TLibFile TFile <|-- TTxtFile

DATA Members

DATA	Type	Description
`cName`	Character	File name (full path)
`hFile`	Numeric	Harbour file handle returned by FOpen()/FCreate()
`nLen`	Numeric	File length in bytes
`nMode`	Numeric	File open mode (0=read, 1=write, 2=read+write)

Methods

Method	Description
`New( cFile, nMode )`	Open an existing file. nMode: 0=read, 1=write, 2=read+write
`Create( cFile, nMode )`	Create a new file (or truncate existing). nMode: 1=write, 2=read+write
`nGetByte()`	Read one byte (0-255) at current position and advance
`nGetWord()`	Read two bytes as a signed 16-bit integer and advance
`cGetStr( n )`	Read n bytes as a character string and advance
`PutByte( n )`	Write one byte at current position and advance
`PutWord( n )`	Write two bytes (16-bit integer) at current position and advance
`PutStr( c )`	Write a character string at current position and advance
`GoTop()`	Seek to beginning of file (position 0)
`GoBottom()`	Seek to end of file
`Skip( n )`	Move forward (positive n) or backward (negative n) n bytes
`GoTo( n )`	Seek to absolute byte position n
`Seek( cStr )`	Search forward for string cStr, return position or 0 if not found
`Count( cStr )`	Count occurrences of string cStr in the file
`DelBytes( n )`	Delete n bytes at current position (shifts remainder left)
`InsBytes( n )`	Insert n zero-bytes at current position (shifts remainder right)
`lEof()`	Return .T. if at end of file
`lBoF()`	Return .T. if at beginning of file
`Close()`	Close the file handle

Example: Read a Binary File Byte by Byte

#include "FiveWin.ch"

function Main()

   local oFile := TFile():New( "c:\data\sample.bin", 0 )
   local nByte, aBytes := {}

   if oFile:hFile != nil
      while ! oFile:lEof()
         nByte := oFile:nGetByte()
         if nByte != -1
            AAdd( aBytes, nByte )
         endif
      endwhile
      oFile:Close()

      ? "Total bytes read:", Len( aBytes )
      ? "First byte:", aBytes[ 1 ]
      ? "Last byte:", aBytes[ Len( aBytes ) ]
   else
      ? "Cannot open file"
   endif

return nil

TFile - Binary File I/O

DATA Members

Methods

Example: Read a Binary File Byte by Byte

See Also