how to write a "od -bc" like function?

[jck11]

hi all
Could any one give me a direction to write a function to match the unix-like
function "od -bc" do.
Now I only get the idea of opening the file.

open(IN, "filename")or die;
my $str=<IN>;
..............
close(IN);

By the way, if the file is a exe or image type, the $str seems don't work
correctly.

 

[John W. Krahn]

hi all
Could any one give me a direction to write a function to match the unix-like
function "od -bc" do.

http://search.cpan.org/src/CWEST/ppt-0.14/bin/od


John

 

[A. Sinan Unur]

hi all
Could any one give me a direction to write a function to match the
unix-like function "od -bc" do.
Now I only get the idea of opening the file.

open(IN, "filename")or die;

Prefer the three-argument form of open.
At least give an indication why the call failed.

open my $in, '<', 'filename'
or die $!;

my $str=<IN>;

Here, you read only one line from the file.

.............
close(IN);

By the way, if the file is a exe or image type, the $str seems don't
work correctly.

Study my hexdump example at:

http://www.unur.com/comp/ppp/hexdump.html

You should be able to adapt that to produce the same output od -bc
produces by changing only the hexdump_line subroutine.

Keep in mind:

You must read the input file in binary mode.

Line-by-line processing does not mean much here as you are trying to
display fixed sized blocks of bytes.


Sinan

 

[Josef Moellers]

hi all
Could any one give me a direction to write a function to match the unix-like
function "od -bc" do.
Now I only get the idea of opening the file.

open(IN, "filename")or die;
my $str=<IN>;
.............
close(IN);

By the way, if the file is a exe or image type, the $str seems don't work
correctly.

Apart from the usual: three-argument "open", lexical filehandles, and
explicit '<':
1. if you're dealing with binary files, you must tell perl this:
"binmode IN;" after open(...), and
2. you're not reading "strings" of *characters* but "blocks" of *binary*
data, so better use "read(...)".

so
perldoc -f binmode
perldoc -f read

 

[John W. Krahn]

Apart from the usual: three-argument "open", lexical filehandles, and
explicit '<':
1. if you're dealing with binary files, you must tell perl this:
"binmode IN;" after open(...), and

Or use the open pragma:

use open IO => ':raw';



perldoc open



John