Q47737: INFO: filelength() Includes EOF Character in Return Value

Article: Q47737
Product(s): Microsoft C Compiler
Version(s): MS-DOS:5.1,6.0,6.00a,6.00ax,7.0; WINDOWS:1.0,1.5; WINDOWS NT:1.0,2.0,2.1,4.0,5.0
Operating System(s): 
Keyword(s): kbcode kbCRT kbVC100 kbVC150 kbVC200 kbVC210 kbVC400 kbVC500 kbVC600
Last Modified: 22-JUL-2001

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The information in this article applies to:

- The C Run-Time (CRT), included with:
   - Microsoft C for MS-DOS, versions 5.1, 6.0, 6.0a, 6.0ax 
   - Microsoft C/C++ for MS-DOS, version 7.0 
   - Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5 
   - Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 2.1, 4.0, 5.0, 6.0 
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SUMMARY
=======

The return value of the filelength() function is the full length of the file in
bytes, including any EOF characters. This return value will be the same as the
file size indicated by the MS-DOS, OS/2, or Windows NT command prompt DIR
command.

MORE INFORMATION
================

The C Run-time included with Visual C++ version 4.0 provides not only the
_filelength() (filelength()) function but also the Microsoft specific
_filelengthi64() function. _filelengthi64() differs from filelength() in its
return type, a 64-bit int (__int64). For more information on _filelength() or
_filelengthi64(), consult the Visual C++ Books Online.

The sample code below demonstrates the use of _filelength().

Sample Code
-----------

  /* Compile options needed: none */ 
  /* CHSIZE.C: This program uses _filelength to report the size
   * of a file before and after modifying it with _chsize.
   */ 

  #include <io.h>
  #include <fcntl.h>
  #include <sys\types.h>
  #include <sys\stat.h>
  #include <stdio.h>

  void main( void )
  {
     int fh, result;
     unsigned int nbytes = BUFSIZ;

     /* Open a file */ 
     if( (fh = _open( "data", _O_RDWR | _O_CREAT, _S_IREAD
                     | _S_IWRITE ))  != -1 )
     {
        printf( "File length before: %ld\n", _filelength( fh ) );
        if( ( result = _chsize( fh, 329678 ) ) == 0 )
           printf( "Size successfully changed\n" );
        else
           printf( "Problem in changing the size\n" );
        printf( "File length after:  %ld\n", _filelength( fh ) );
        _close( fh );
     }
  }

Additional query words:

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Keywords          : kbcode kbCRT kbVC100 kbVC150 kbVC200 kbVC210 kbVC400 kbVC500 kbVC600 
Technology        : kbVCsearch kbAudDeveloper kbCRT
Version           : MS-DOS:5.1,6.0,6.00a,6.00ax,7.0; WINDOWS:1.0,1.5; WINDOWS NT:1.0,2.0,2.1,4.0,5.0
Issue type        : kbinfo

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