Rouben Rostamian wrote:
Consider the following demo program:
#include <stdio.h>
int main(void)
{
unsigned char c;
for (c=0; c<15; c++) putchar(c);
return 0;
}
As is, the output of the program is platform-dependent.
For instance, in the UNIX environment, it puts 15 characters
to stdout. Under windows it puts out at least 16, because c=10
gets translated to newline+carriage return.
This brings me to:
Question: Is it possible to close stdout then reopen it in binary
mode in a platform-independent way?
If that were possible, then the binary-mode output of the program
would be the same on all platforms.
The purpose of my real program (not this demo,) is to act as a
filter from stdin to stdout, therefore fopen(filename, "wb") is
of not much help.
This is handled by freopen.
if (freopen(NULL, "wb", stdout)) {...}
Note that it may fail, and has some implementation dependancies.From N869:
7.19.5.4 The freopen function
Synopsis
[#1]
#include <stdio.h>
FILE *freopen(const char * filename,
const char * mode,
FILE * restrict stream);
Description
[#2] The freopen function opens the file whose name is the
string pointed to by filename and associates the stream
pointed to by stream with it. The mode argument is used
just as in the fopen function.215)
____________________
215The primary use of the freopen function is to change the
file associated with a standard text stream (stderr,
stdin, or stdout), as those identifiers need not be
modifiable lvalues to which the value returned by the
fopen function may be assigned.
[#3] If filename is a null pointer, the freopen function
attempts to change the mode of the stream to that specified
by mode, as if the name of the file currently associated
with the stream had been used. It is implementation-defined
which changes of mode are permitted (if any), and under what
circumstances.
[#4] The freopen function first attempts to close any file
that is associated with the specified stream. Failure to
close the file is ignored. The error and end-of-file
indicators for the stream are cleared.
Returns
[#5] The freopen function returns a null pointer if the open
operation fails. Otherwise, freopen returns the value of
stream.
--
Chuck F (cb********@yahoo.com) (cb********@worldnet.att.net)
Available for consulting/temporary embedded and systems.
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