Open a file in binary mode

[Hatzigiannakis Nikos]

I have written the following code in DEV C++ but the produced file is a
normal text file (you can type it in command line). I was expecting that the
numeric values would have written in their binary internal representation
and not as pure text.

What have I done wrong?

#include <iostream>
#include <iomanip>
#include <fstream>
using namespace std;

main ()
{
ofstream myfile;
myfile.open("datafile",ios::out|ios::binary);
myfile<<123<<34<<12.123<<"start"<<endl;
myfile<<"end";
myfile.close();
}

[Ian Collins]

Hatzigiannakis Nikos wrote:

I have written the following code in DEV C++ but the produced file is a
normal text file (you can type it in command line). I was expecting that the
numeric values would have written in their binary internal representation
and not as pure text.

What have I done wrong?

#include <iostream>
#include <iomanip>
#include <fstream>
using namespace std;

main ()
{
ofstream myfile;
myfile.open("datafile",ios::out|ios::binary);

This sets the file mode, not the stream.

--
Ian Collins.

[Hatzigiannakis Nikos]

and how can I have a binary stream?!

? "Ian Collins" <ia******@hotmail.com?????? ??? ??????
news:5p************@mid.individual.net...

Hatzigiannakis Nikos wrote:

>I have written the following code in DEV C++ but the produced file is a
normal text file (you can type it in command line). I was expecting that
the
numeric values would have written in their binary internal representation
and not as pure text.

What have I done wrong?

#include <iostream>
#include <iomanip>
#include <fstream>
using namespace std;

main ()
{
ofstream myfile;
myfile.open("datafile",ios::out|ios::binary);

This sets the file mode, not the stream.

--
Ian Collins.

[Gianni Mariani]

Hatzigiannakis Nikos wrote:

and how can I have a binary stream?!

Usually you use the read() and write() methods to do that.

It can be tricky to get it right, what exactly are you trying to do ?

[Hatzigiannakis Nikos]

was trying to demonstrate the difference between the two modes. I cannot
see any since the output is exactly the same either in text or binary mode,
in the given code

? "Gianni Mariani" <gi*******@mariani.ws?????? ??? ??????
news:47********@news.eftel.com.au...

Hatzigiannakis Nikos wrote:

>and how can I have a binary stream?!

Usually you use the read() and write() methods to do that.

It can be tricky to get it right, what exactly are you trying to do ?

[Pete Becker]

On 2007-11-13 06:39:45 -0500, "Hatzigiannakis Nikos" <ni***@ypai.grsaid:

? "Gianni Mariani" <gi*******@mariani.ws?????? ??? ??????
news:47********@news.eftel.com.au...

>Hatzigiannakis Nikos wrote:

>>and how can I have a binary stream?!

Usually you use the read() and write() methods to do that.

It can be tricky to get it right, what exactly are you trying to do ?

was trying to demonstrate the difference between the two modes. I cannot
see any since the output is exactly the same either in text or binary mode,
in the given code

Inserters do formatting, regardless of whether the stream is in binary
or text mode. write() outputs binary data, regardless of whether the
stream is in binary or text mode.

The difference between the two modes is whether the stream translates
"special" characters. In particular, '\n' represents a newline, and in
text mode the stream writes whatever is appropriate on the system where
it's running to represent the end of a line. In binary mode it's just
the value \x0D.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

[red floyd]

Pete Becker wrote:

The difference between the two modes is whether the stream translates
"special" characters. In particular, '\n' represents a newline, and in
text mode the stream writes whatever is appropriate on the system where
it's running to represent the end of a line. In binary mode it's just
the value \x0D.

Uh, Pete, isn't that '\x0a'? I thought '\r' was '\x0d'.

[Pete Becker]

On 2007-11-13 09:13:58 -0500, red floyd <no*****@here.dudesaid:

Pete Becker wrote:

>The difference between the two modes is whether the stream translates
"special" characters. In particular, '\n' represents a newline, and in
text mode the stream writes whatever is appropriate on the system where
it's running to represent the end of a line. In binary mode it's just
the value \x0D.

Uh, Pete, isn't that '\x0a'? I thought '\r' was '\x0d'.

You're probably right. But on further reflection, it's neither. For
some reason I thought the standard specified the value of '\r' and
'\n'. But that's a hallucination. The value depends on the compiler.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

[red floyd]

Pete Becker wrote:

On 2007-11-13 09:13:58 -0500, red floyd <no*****@here.dudesaid:

>Pete Becker wrote:

>>The difference between the two modes is whether the stream translates
"special" characters. In particular, '\n' represents a newline, and in
text mode the stream writes whatever is appropriate on the system where
it's running to represent the end of a line. In binary mode it's just
the value \x0D.

Uh, Pete, isn't that '\x0a'? I thought '\r' was '\x0d'.

You're probably right. But on further reflection, it's neither. For some
reason I thought the standard specified the value of '\r' and '\n'. But
that's a hallucination. The value depends on the compiler.

That makes sense, since it would be dependent on the execution character
set (0x0a and 0x0d are ASCII, but EBCDIC would probably be quite different).

[Pete Becker]

On 2007-11-14 05:18:49 -0500, James Kanze <ja*********@gmail.comsaid:

On Nov 13, 2:26 pm, Pete Becker <[e-mail]:

>On 2007-11-13 06:39:45 -0500, "Hatzigiannakis Nikos" <[e-mail]:

>>? "Gianni Mariani" <[e-mail]?????? ??? ??????
news:47********@news.eftel.com.au...
Hatzigiannakis Nikos wrote:
and how can I have a binary stream?!

>>>Usually you use the read() and write() methods to do that.

>>>It can be tricky to get it right, what exactly are you trying to do ?
was trying to demonstrate the difference between the two modes. I cann

ot

>>see any since the output is exactly the same either in text or binary m

ode,

>>in the given code

>Inserters do formatting, regardless of whether the stream is in binary
or text mode. write() outputs binary data, regardless of whether the
stream is in binary or text mode.

And when writing to a file, the embedded locale does code
translation, regardless of the mode or whether you use inserts
or unformatted output functions.

And since it's not affected by the mode, it's irrelevant to this discussion.

>

>The difference between the two modes is whether the stream translates
"special" characters.

There's a lot more to it than that.

Indeed. But giving long technical explanations to beginners is a good
way to discourage them.

>In particular, '\n' represents a newline,

Internally.

>and in text mode the stream writes whatever is appropriate on
the system where it's running to represent the end of a line.

Again, it's more subtle than that.

Again, fully detailed explanations are often counterproductive.

>

>In binary mode it's just the value \x0D.

Not on my machines. It's been 0x0A on every system I've seen.

This has already been dealt with in two followup messages. But thanks
for piling on.

--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)