Tutorial Addendum on Perl - Allotment A - Ascribe and Achievement in Bifold Approach

This affiliate describes:

    

    
• How to accessible files for ascribe in bifold mode.
  
      



    
• How to accessible files for achievement in bifold mode.
  
      



    
• Example program to archetype bifold files
  
      



    
• Example program to catechumen bifold data to hex numbers.
  
      



    

Opening Files for Bifold Input

    

If you wish to accessible a book and apprehend its agreeable in bifold mode, you should

    

use the afterward functions:

    

    
• open() to accessible the book to a book handle.
  
      



    
• binmode() to set the book handle to bifold mode.
  
      



    
• read() to apprehend data from the book handle.
  
      



    
• close() to abutting the book handle.
  
      



    

Descriptions and sample codes of open() and close() are in the antecedent chapter.

    

The syntax of binmode() is actual simple:

    

    
   binmode(file_handle);

    

The syntax of read() is added complex:

    

    
rc = read(file_handle, buffer, length, offset);

    
rc = read(file_handle, buffer, length);

    

where "buffer" is a scalar capricious area the inputted bytes will be stored;

    

"length" is the amount of bytes requested to be inputted; "rc" is the

    

actual amount of bytes inputted; "offset" is an alternative amount to specify

    

where in the scalar capricious to activate to abundance the inputted bytes.

    

Opening Files for Bifold Output

    

If you wish to accessible a book and address bifold data to it, you should

    

use the afterward functions:

    

    
• open() to accessible the book to a book handle.
  
      



    
• binmode() to set the book handle to bifold mode.
  
      



    
• print() to address data to the book handle.
  
      



    
• close() to abutting the book handle.
  
      



    

Note that the print() action can be acclimated in both bifold approach and argument mode.

    

In bifold mode, print() will not catechumen to in Windows system.

    

Copy Bifold Files - Copy.pl

    

As a simple archetype program of ascribe and achievement data in bifold mode, I wrote Copy.pl

    

to archetype bifold files:

    

 

    
#- Copy.pl

    
#- Absorb (c) 1995 by Dr.  Yang

    
#

    
   ($in, $out) = @ARGV;

    
   die "Missing ascribe book name.
" unless $in;

    
   die "Missing achievement book name.
" unless $out;

    
   $byteCount = 0;

    
   open(IN, "< $in");

    
   binmode(IN);

    
   open(OUT, "> $out");

    
   binmode(OUT);

    
   while (read(IN,$b,1)) {

    
      $byteCount++;

    
      print(OUT $b);

    
   }

    
   close(IN);

    
   close(OUT);

    
   book "Number of bytes affected = $byteCount
";

    
   exit;

    

To analysis this program, I acclimated the afterward commands:

    

 

    
>copy c:winntsystem32mem.exe mem.exe

    
        1 file(s) copied.

    
>Copy.pl mem.exe mem_copy.exe

    
Number of bytes affected = 39386

    
>mem_copy

    
    655360 bytes absolute accepted memory

    
    655360 bytes accessible to MS-DOS

    
    633776 better executable program size

    
   1048576 bytes absolute abutting continued memory

    
         0 bytes accessible abutting continued memory

    
    941056 bytes accessible XMS memory

    
           MS-DOS citizen in Top Anamnesis Area