Ok, i have already searched through the newbie forum for the answer to this so hold your flames...

I have been programming in C/C++ for quite some time now but have never done so in a Linux environment.

I have just installed Red Hat 8.0 and am using the KDE GUI.

I am trying to compile and run a simple hello world program with this code:

#include <iostream.h>

int main()
{
cout << "Hello World!" << endl;
return 0;
}

Simple enough right? Below is the output I get when I try to compille it. Please help me make since of what it is I need to do to produce C/C++ programs in a Linux Environment.


[wbsmith2@dhcppc1 programs]$ gcc -o hello hello.cpp
In file included from /usr/include/c++/3.2/backward/iostream.h:31,
from hello.cpp:1:
/usr/include/c++/3.2/backward/backward_warning.h:32:2: warning: #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. Examples include substituting the <X> header for the <X.h> header for C++ includes, or <sstream> instead of the deprecated header <strstream.h>. To disable this warning use -Wno-deprecated.
/tmp/ccYveVmw.o: In function `main':
/tmp/ccYveVmw.o(.text+0x14): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
/tmp/ccYveVmw.o(.text+0x21): undefined reference to `std::cout'
/tmp/ccYveVmw.o(.text+0x26): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
/tmp/ccYveVmw.o(.text+0x2f): undefined reference to `std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))'
/tmp/ccYveVmw.o: In function `__static_initialization_and_destruction_0(int, int)':
/tmp/ccYveVmw.o(.text+0x5c): undefined reference to `std::ios_base::Init::Init[in-charge]()'
/tmp/ccYveVmw.o: In function `__tcf_0':
/tmp/ccYveVmw.o(.text+0x8b): undefined reference to `std::ios_base::Init::~Init [in-charge]()'
/tmp/ccYveVmw.o(.eh_frame+0x11): undefined reference to `__gxx_personality_v0'
collect2: ld returned 1 exit status
[wbsmith2@dhcppc1 programs]$ ls
hello.cpp



thanks in advance...

ok, i figured part of this out....

first off, it appears as if I should be using the g++ compiler instead of the gcc compiler...

when I was at school it never seemed to matter...

/me shrugs

next, to run the executable type "./a.out" or whatever it is named

in my case it was "./hello"

now, can anyone help me out with why <iostream.h> contains a deprecated header?

trying using "#include <iostream>" without the .h, then you won't get the error message. As for why iostream.h is old or whats new in iostream, i couldn't tell you.

thanks man....

that and this line needs to be added;

using namespace std;

WTF! i just graduated in May(BS in Comp Engineering) and NEVER was I introduced to this nor did I ever have to use it...

that "using namespace std;" is in my c++ book... but I never have to use it. I think it just tells the compiler to look in the "standard" place for the header files.

you're right on with the ./a.out . in the *nix systems, a "." means "current directory" and ".." means next directory up. so if you want to use an executable from your current directory, you do ./ . if you make another directory in there and change into it (cd), you can run that same binary with ../a.out. or, cd back up with cd .. ( or cd ../ to go along with what's stated above)

if you want to just be able to use your programs from anywhere on your system without having to type the full path, you need to put it in /bin, /usr/bin, or anything that gets spit out when you do "echo $PATH". you can also make a directory for only your programs and add that directory to your $PATH variable. open up the file ~/.bash_profile (files and directories w/ a "." in front of them are "hidden"... to see them all when you are in that directory do "ls -a").... also the "~/" means "home directory"... bash understands what you are talking about. this will be /root for the root user and /home/user for any other user.... ooh yeah.. back to $PATH.... open up your ~/.bash_profile, and you'll see a line like PATH=/bin:/usr/bin:, ect.. just put your personal program directory at the end and make sure each of the paths are separated by a colon.

well, have fun!

-Adam

p.s.- if you have gcc 3.1 (find out with gcc -v) there is a bug in <string.h>, so if you're planing on using that... you should upgrade to gcc-3.2

Well, you're naming a C program as a C++ program. It creates trouble. Rename the file to hello.c and it will compile without a warning.