C++: linker subsystem

Question

I am a beginner in C++, and I am here to learn.

First of all, I made some programs in Borland C++, at school, but my school doesn't have Visual C++, and I don't have anybody to teach me how to program in Visual C++.

The problem is that when I try to change the linker subsystem (project settings) to Windows (/SUBSYSTEM:WINDOWS), I get this in output window:

1>------ Build started: Project: hew, Configuration: Debug Win32 ------
1>  main.cpp
1>c:\users\mxmike\documents\visual studio 2010\projects\hew\main.cpp(1): fatal
error C1083: Cannot open include file: 'iostream.h': No such file or directory
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

My code is really simple:

#include <iostream.h>
#include <stdlib.h>

int main(int f)
{
    int i=1;
    return 1;
}

I simply don't get it. Would someone be so kind do explain to me?
Thank you for reading!

Or not mention std lib.h, in whichever flavor, since nothing it declares is used. That way I won't have to point out that stdlib.h works just fine. — Pete Becker, Apr 04 '13 at 20:36
You should be returning 0 on success as well. `main()` will do that for you if you leave it out. I'll be surprised if your compiler supports that signature, too. It's only required to support `int main()` and `int main(int, char**)`. — chris, Apr 04 '13 at 20:37

Joseph Mansfield · Accepted Answer · 2013-04-04T20:39:48.543

There is no <iostream.h> header. The standard library header for I/O is <iostream>. None of the C++ standard library headers end with .h.

The headers that do exist that end with .h are from the C standard library. So, for example, <stdlib.h> is a C standard library header. The C++ standard does make these headers available, but it also provides its own alternatives with almost identical contents. Simply remove the .h and add a c to the beginning. So the C++ version of <stdlib.h> is <cstdlib>.

Whether you actually need the contents of either <stdlib.h> or <cstdlib> is a different matter. Most of the functionality has improved C++ counterparts in C++-specific headers. For example, these C headers provide malloc, but you should instead be using new-expressions in C++.

Also note that returning 1 from main is typically a sign of failure. To indicate a successful execution, do return 0; instead.

score 1 · Answer 2 · answered Apr 04 '13 at 20:38

1

There are two standard types of header files in C++. Those that derive from C, such as < stdlib.h > which in C++ should be included as < cstdlib > (take off the .h and prefix with a c) and those like < iostream > which is a C++ header file which replaces the C < stdio.h >.

What you want is:

#include <cstdio>
#include <cstdlib>

or

#include <iostream>
#include <cstdlib>

depending on which functionality/functions you call in your code (in the case you supply none so both should work).

Regards,

Jason Posit

answered Apr 04 '13 at 20:38

Jason Posit

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@PeteBecker, Sure they work, but it's best to use the C++ version and `std::xxx`. – chris Apr 04 '13 at 20:40
@chris - what benefit do you see from using the C++ versions? Other than not having to point out that they provide exactly the same functions... – Pete Becker Apr 04 '13 at 20:42
@PeteBecker, I'm trying to find the question about it that I remember seeing. – chris Apr 04 '13 at 20:50
@PeteBecker, Looks like it isn't as good as I remembered: http://stackoverflow.com/questions/5079325/should-i-include-stddef-h-or-cstddef – chris Apr 04 '13 at 20:56
@chris - ``. The reasons given for insisting on the C++ versions are usually overinflated personal preferences. There is no sound technical reason for choosing either way (especially now that C++11 has recognized reality and removed the unenforceable requirement that the C++ headers not dump the C names into the global namespace). – Pete Becker Apr 04 '13 at 21:03
@PeteBecker, It's a real shame we have two versions of them then. At least modules are a proper solution. They fix compilation times, they fix macros, and they fix polluting. – chris Apr 04 '13 at 21:14
@chris - the current scheme is the result of wishful thinking on the part of some members of the standards committee the first time around. – Pete Becker Apr 04 '13 at 23:21
@PeteBecker It was a nice thought at the time, but it ended up being totally impractical. – chris Apr 04 '13 at 23:23

C++: linker subsystem

2 Answers2