Simple question about binmode

[emcee2k]

When I run the following code, it creates a 1063 byte file on Win32:

open(F, 'textfile.txt');
read(F, $txtPreview, 1024, 0);
close(F);
open(TL, '>textpreview.txt');
print TL $txtPreview;
close(TL);

There's 39 line breaks in the file it creates, so that explains the
file size of 1063 instead of 1024. However, with this code I expected
to get a file of 1024, but I still got 1063:

open(F, 'textfile.txt');
binmode(F);
read(F, $txtPreview, 1024, 0);
close(F);
open(TL, '>textpreview.txt');
print TL $txtPreview;
close(TL);

So what do I have to do to insure that the length argument to the read
function is treated as the amount of bytes to be read, rather than the
amount of characters?

 

[Tad J McClellan]

with this code I expected
to get a file of 1024, but I still got 1063:

open(F, 'textfile.txt');
binmode(F);
read(F, $txtPreview, 1024, 0);
close(F);
open(TL, '>textpreview.txt');
print TL $txtPreview;
close(TL);

You have not binmode()ed your output filehandle...

read() has a return value (as does open() and close()).

You should check the return values.

The length() function will tell you the size of $txtPreview.

 

[Gunnar Hjalmarsson]

When I run the following code, it creates a 1063 byte file on Win32:

open(F, 'textfile.txt');
read(F, $txtPreview, 1024, 0);
close(F);
open(TL, '>textpreview.txt');
print TL $txtPreview;
close(TL);

There's 39 line breaks in the file it creates, so that explains the
file size of 1063 instead of 1024.

Then textfile.txt is most likely *nix formated.

However, with this code I expected
to get a file of 1024, but I still got 1063:

open(F, 'textfile.txt');
binmode(F);
read(F, $txtPreview, 1024, 0);
close(F);
open(TL, '>textpreview.txt');
print TL $txtPreview;
close(TL);

It's TL you need to binmode to prevent Win32 from adding \015 to each line.

So what do I have to do to insure that the length argument to the read
function is treated as the amount of bytes to be read, rather than the
amount of characters?

I don't think your analysis is correct.