CX-Post: hello world

[Tim Judd]

I must not be grasping anything here.

Just a simple application, as follows (as any first-program is...)

----
#include <iostream.h>

int main() {
cout <<"hello world";
return 0;
}
----

never compiles! Tried it on FreeBSD, OpenBSD, Windows (under Visual C++ for
Console App), OS X developer tools. THEY ALL complain!
pretty much the same reason too!

/tmp/ccJ31810.o: In function `main':
/tmp/ccJ31810.o(.text+0xf): undefined reference to `cout'
/tmp/ccJ31810.o(.text+0x14): undefined reference to
`ostream:perator<<(char const *)'
collect2: ld returned 1 exit status


But... I thought the #include was supposed to bring in the definitions from
that file before checking the code for execution problems.

I don't understand why it won't work, no matter the tutorials I see, books I
read, articles I read! Can someone point me in the right direction, a
utterly clueless newbie! (yes, I called myself that, so you can call me
that ONCE, too!)

Appreciate it in advance, email is spam-blocked, remove the single period
PRIOR to the @ sign to reply by mail.

--Tim

 

[Kelvin@!!!]

well, you forgot something in ur code..
first C++ standard encourages you to use
#include <iostream>
and cout should really be written as std::cout in your case

if you dont want to write std::cout through out your whole program
you should put
using namespace std;
before your main() function
so that you can just write cout in the following lines

and i also have a question here

can i put the "using namespace bla" in the middle of my code?
or can i make it effective in only a certain block of code??
thank you very much

 

[JaSeong Ju]

Do this instead:

#include <iostream>


using namespace std;


int main() {
cout << "hello world" << endl;
return 0;
}



iostream.h is deprecated, the standard C++ is to use
iostream without .h

the undefined reference to cout appeared because
the "using namespace std" was not there.

see http://www.research.att.com/~bs/bs_faq2.html

 

[JaSeong Ju]

Do this instead:

#include <iostream>


using namespace std;


int main() {
cout << "hello world" << endl;
return 0;
}



iostream.h is deprecated, the standard C++ is to use
iostream without .h

the undefined reference to cout appeared because
you had iostream.h instead of iostream.

see http://www.research.att.com/~bs/bs_faq2.html

 

[Buster]

I must not be grasping anything here.

Just a simple application, as follows (as any first-program is...)

----
#include <iostream.h>

int main() {
cout <<"hello world";
return 0;
}

There shouldn't be a link error. Did you use
"gcc" instead of "g++" for linking?

 

[John Harrison]

I must not be grasping anything here.

Just a simple application, as follows (as any first-program is...)

----
#include <iostream.h>

int main() {
cout <<"hello world";
return 0;
}
----

never compiles! Tried it on FreeBSD, OpenBSD, Windows (under Visual C++ for
Console App), OS X developer tools. THEY ALL complain!
pretty much the same reason too!

[snip]

Clueless tutorials more like. The correct program is

#include <iostream>

int main() {
std::cout <<"hello world";
}

<iostream> not <iostream.h>

std::cout not cout

return is unnecessary (not an error however).

Get a decent book on C++, one that actually contains accurate and up to date
information. I'd make a recommendation but I'd need to what what your
general level of experience with programming is. Do you know any other
languages for instance?

john

 

[John Harrison]

iostream.h is deprecated, the standard C++ is to use

iostream without .h

iostream.h is not deprecated, it is non-standard.

Deprecated implies that it used to be standard, still is standard, but may
become non-standard in the future. iostream.h has never been part of
standard C++.

john

 

[Kevin Goodsell]

I must not be grasping anything here.

*Why* did you cross-post this to comp.lang.c? They don't want to see
your C++ programs over there. I suggest you apologize to that group, and
be more careful in the future.

Just a simple application, as follows (as any first-program is...)

int main() {
cout <<"hello world";

cout resides in namespace std. You have to account for that somehow. For
example, you can do this:

std::cout << "hello world\n";

Or this:

using std::cout;
cout << "hello world\n";

Or this:

using namespaces std;
cout << "hello world\n:'

But in any case you need to properly terminate your output with a
newline if you want your code to be correct and portable.

return 0;
}

It sounds like you need better tutorials. Most tutorials on the web are
worse than useless. You might try Bruce Eckel's book, "Thinking in C++",
which is free to download.

-Kevin

 

[Kevin Goodsell]

Do this instead:

Please watch the cross-post list. Do not cross-post C++ code to comp.lang.c.

#include <iostream>


using namespace std;


int main() {
cout << "hello world" << endl;
return 0;
}



iostream.h is deprecated, the standard C++ is to use
iostream without .h

iostream.h is not deprecated. The standard cannot deprecate what it does
not contain, and iostream.h has never been standard C++.

-Kevin

 

[Kevin Goodsell]

Please watch the cross-post list. Do not post about C++ in comp.lang.c.

Also, please don't top-post. This is in the FAQ, section 5 (regarding
netiquette).

well, you forgot something in ur code..
first C++ standard encourages you to use
#include <iostream>
and cout should really be written as std::cout in your case

if you dont want to write std::cout through out your whole program
you should put
using namespace std;
before your main() function
so that you can just write cout in the following lines

and i also have a question here

can i put the "using namespace bla" in the middle of my code?
or can i make it effective in only a certain block of code??

Yes. It takes effect at the point in the source where it occurs, and
continues until the end of the block in which it occurs, or the end of
the translation unit if it's not inside a block.

-Kevin

 

[Martin Ambuhl]

I must not be grasping anything here.

Just a simple application, as follows (as any first-program is...)

----
#include <iostream.h>

int main() {
cout <<"hello world";
return 0;
}

If you are going to post to comp.lang.c, post C. If you want to use
C++, post to comp.lang.c++. For one of the two newsgroups you posted
to, there is no <iostream.h> (or <iostream>) header, there is no
predefined variable cout (or std::cout), and the symbol "<<" is always,
other than in data or comments, a left shift operator. If the line
containing 'cout' is intended to output the text "hello world", then the
behavior of this program would, as well be undefined, since the last
line of output does not end with an end-of-line '\n'.

Here is your code, corrected for comp.lang.c:

#include <stdio.h>
int main(void)
{
puts("Hello world");
return 0;
}

Follow-ups set to comp.lang.c++, since that where your question belongs.

 

[Buster]

Clueless tutorials more like. The correct program is

#include <iostream>

int main() {
std::cout <<"hello world";
}

Wrong (you have to output a whole line).

 

[Rolf Magnus]

*Why* did you cross-post this to comp.lang.c? They don't want to see
your C++ programs over there. I suggest you apologize to that group,
and be more careful in the future.

Actually, it has more relevance than you might think. The OP seems to
have compiled and linked his code with a C compiler, maybe because he
doesn't actually know the difference between C and C++. The error
message looks like the typical message you get if you try to link C++
code using gcc instead of g++.

Or this:

using namespaces std;
cout << "hello world\n:'

I don't think that this will work ;-)

 

[Dan Pop]

I must not be grasping anything here.

Most likely, since you appear to be a patent idiot. Otherwise, you'd have
never crossposted your question to comp.lang.c.

Dan

 

[Gary Labowitz]

If you are going to post to comp.lang.c, post C. If you want to use
C++, post to comp.lang.c++. For one of the two newsgroups you posted
to, there is no <iostream.h> (or <iostream>) header, there is no
predefined variable cout (or std::cout), and the symbol "<<" is always,
other than in data or comments, a left shift operator. If the line
containing 'cout' is intended to output the text "hello world", then the
behavior of this program would, as well be undefined, since the last
line of output does not end with an end-of-line '\n'.

Here is your code, corrected for comp.lang.c:

#include <stdio.h>
int main(void)
{
puts("Hello world");
return 0;
}

Just a note: Using Dev-Cpp the OP code compiles and executes.
There is a backward library which contains iostream.h that 1) includes
iostream, and 2) has a bunch of using's for all the iostream
functions.
I am undecided if this is a good thing (allows new users to do dumb
things) or a bad thing (allows new users to do dumb things).
g++ does issue a warning message which reads
#warning This file includes at least one deprecated or antiquated
header. Please consider using one of the 32 headers found in section
17.4.1.2 of the C++ standard. ...
I believe this is all correct behaviour.

 

[Christopher Benson-Manica]

Wrong (you have to output a whole line).

If C++ is like C in this respect, it's actually implementation-defined
whether a newline is required (isn't it?).

 

[Buster]

If C++ is like C in this respect, it's actually implementation-defined
whether a newline is required (isn't it?).

Exactly.

 

[Kevin Goodsell]

Kevin Goodsell wrote:




I don't think that this will work ;-)

Heh. Obviously I did actually manage to hit the shift key, but missed
the quote key. After that I probably tried to fix it, and in my usual
fashion hit some lengthy sequence of almost-but-not-quite-right keys,
interspersed with several backspaces, until I had something that
registered in my brain as being correct. Oh, well.

-Kevin