What Can I do with "ostream"

[LewGun]

Usually， when we program with C++, we like to include the
header"iostream", but it's too big, so i want to use the header
"ostream" (only use it to output), as follows ,there is a
piece of code what i think can do this.. but the compiler can't give
me a good news. what can i do.

//------------------------------------------------------------------
// source code
//------------------------------------------------------------------
#include <ostream>


int main(int argc, char **argv)
{
ostream os;

int forTest1 = 1;
char forTest2 = '1';
os << forTest << " " << forTest2 << "\n";

return 0;
}

// ps: compiler : VS2003.net

 

[Chris ( Val )]

Usually， when we   program with C++, we like to include the
header"iostream", but it's too big, so i want to use the header
"ostream"    (only use it to output), as follows ,there is a
piece of code what i think can do this.. but the compiler can't give
me a good news.  what can i do.

//------------------------------------------------------------------
// source code
//------------------------------------------------------------------
#include <ostream>

int main(int argc, char **argv)
{
ostream os;

std:stream& os( std::cout );

Alos note that you did not specify a
namespace in your code.

 

[Guest]

std:stream& os( std::cout );

Also not that std::cout is declared in <iostream>.

To the OP: In what way is <iostream> to large? If it is you can either
use <fstream> and write to a file, or use <cstdio> and use the C
functions to write to stdout.

 

[James Kanze]

Usually， when we program with C++, we like to include the
header"iostream", but it's too big, so i want to use the header
"ostream" (only use it to output), as follows ,there is a
piece of code what i think can do this.. but the compiler can't give
me a good news. what can i do.

//------------------------------------------------------------------
// source code
//------------------------------------------------------------------
#include <ostream>

int main(int argc, char **argv)
{
ostream os;

int forTest1 = 1;
char forTest2 = '1';
os << forTest << " " << forTest2 << "\n";

return 0;
}

// ps: compiler : VS2003.net

With just an ostream, you can't do very much; you need an
ofstream, or something along those lines. But because ofstream
derives from ostream, most of the source code doesn't need to
know about it. So typically, you'll #include <iostream> and
<fstream> in main, or in whatever function evaluates the command
line args, and <ostream> everywhere else (and just <iosfwd> in
your headers).

 

[Chris ( Val )]

Also not that std::cout is declared in <iostream>.

[snip]

My apologies, I was completely focused on the syntax

Thanks for the correction.