Problem with formatting output

I have been trying to format output so that it gives two decimal accuracy when it is displayed. The problem I am having is that the "fixed" manipulator for output creates an error.

Code:

  #include<iostream.h>
#include<iomanip.h>
//using namespace std;


int main()
{

	cout << "The center of gravity for the loaded plane is " << setiosflags(ios::fixed) << setprecision(2) << CG_filled << " inches from the nose of the aircraft." << endl;

	return 0;
}

I was searching around and found the "setiosflags(ios::fixed)" and it works, but I don't know how it works. If I remove the .h from the pre-processor directives and remove the remark symbol before the namespace statement it will allow me to place just "fixed" in the cout statement. If someone could help me understand why I need to use the namespace std or what the setiosflags does, that would be greatly appreciated.

<xxxx.h> was the old way for standard header files. The new header files drop the 'h'. Like so:

Code:

#include <iostream>
using namespace std;
int main()
{
  cout << "Hello world!" << endl;
  return 0;
}

The old ".h" way has been deprecated, so although it is still possible to use that now, that won't always be the case in the future. What you should do is use the new libraries.

Now as for that whole std thingie, that's a namespace. In the new and improved libraries, all of the identifiers have been placed in a namespace called std to avoid potential name conflicts. The easiest way to ensure that you are using the whole std namespace is as shown above. There are other ways, however, that some people will argue are better/worse.

Code:

#include <iostream>
using std::cout;
using std::endl;
int main()
{
  cout << "Hello World!" << endl;
  return 0;
}
/* OR */
#include <iostream>
int main()
{
  std::cout << "Hello World!" << std::endl;
  return 0;
}

If you feel the need to know exactly what namespaces are, a quick search will probably yield many answers.

<iostream.h> and <iomanip.h> are not deprecated, they're simply non-standard. It's the older C-library headers like <stdio.h> and <stdlib.h> that are deprecated, in favour of <cstdio> and <cstdlib> and the like, but they're still standard.

The distinction is important; any conforming compiler (for the current version of the C++ standard at least) is required to provide <stdio.h>, <stdlib.h> etc. so you can rely on them being available. They're not required to provide <iostream.h>, <iomanip.h> etc (and not all compilers do).

Even so, they'd better do so, just for compatibility with older code. Besides, it does not cost them much. So one can consider that these headers are present where the standard ones are, in my opinion.

^ i don't think so... I think it's better just to tweak your code to make it more standards-compliant, because if you don't, eventually they may reach a point where backward-compatability may not be practical anymore, then all the programs you still have conforming to pre-standard days will need ALOT of tweaking...

Originally posted by lyx
Even so, they'd better do so, just for compatibility with older code. Besides, it does not cost them much. So one can consider that these headers are present where the standard ones are, in my opinion.

The C++ standard came out in 1998; we've already been through a period of 5 years where those older versions were retained for reasons of backwards compatibility. Compilers are now starting to drop the older headers. You can consider them to be present if you wish, but your next compiler may not ;-)

Thanks for the help. I didn't realize that they were actually different libraries. I thought it was just a naming convention. Could someone please explain what the setiosflags and ios::fixed do to the output. It has been a while since I have done any programming, so I remember that :: is a scope operator, but I can't remember what that does. I might not have even learned it in high school to begin with, but it is something i'd like to learn. Thanks again to all who contributed.

I was just saying that you can consider that, to my mind. I wasn't saying to code non-standard when you can do so.
Actually, I don't see the point of deleting them, it does not bring anything good to compilers...

Google does wonders.

http://ranger.uta.edu/~springst/SettingFlags.html