Dear All

I am a beginner to learn C++. I am following an on-line tutorial. When I try the first C++ program as described in the tutorial (which is supposed to work without any problem, as it is said in the tutorial), I got many error message. The folllowing is the program (I name it as test.cpp:






I am using Suse 10.0 linux and the gcc compiler installed by Suse 10.0. After I gcc the programm above ( gcc test.cpp ) I got the error message. When I try to correct the error, and re-compile it, I got other error message!

Can some one point out what mistake I made? Or can you kindly supply me a workable, small program that will run under gcc compiler? I just want to get a rough idea about how C++ works.

Try this code with g++ test.cpp

__________________
Gravitation is not responsible for people falling in love.
-Albert Einstein

Also, iostream.h is deprecated. Use <iostream> and put after the include statement. And if the tutorial uses iostream.h, a more up-to-date tutorial wouldn't hurt...

Thanks for all your kindly help. I tried all the suggestion, here is what I got:


#include <iostream>
int main();
{
std:: cout << "Hello World!\n";
return 0;
}


After I g++ above, the following error message appear:

test.cpp:3: error: expected unqualified-id before ‘{’ token



Next I delete the semicolon for line 2 (int main(), and the program became


#include <iostream>
int main()
{
std:: cout << "Hello World!\n";
return 0;
}


After I g++ again, I got the file a.out (what should I do next?); But If I use gcc, I got many error message (see following):


doudou66@linux:~/C++> gcc test.cpp
/tmp/ccvWewmo.o: In function `main':
test.cpp.text+0x25): undefined reference to `std::cout'
test.cpp.text+0x2a): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std:perator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
/tmp/ccvWewmo.o: In function `__tcf_0':
test.cpp.text+0x47): undefined reference to `std::ios_base::Init::~Init()'
/tmp/ccvWewmo.o: In function `__static_initialization_and_destruction_0(int, int)':
test.cpp.text+0x74): undefined reference to `std::ios_base::Init::Init()'
/tmp/ccvWewmo.o.eh_frame+0x11): undefined reference to `__gxx_personality_v0'
collect2: ld returned 1 exit status



The next thing I did is to add using namespace std, so the program became:



#include <iostream>
using namespace std;
int main()
{
std:: cout << "Hello World!\n";
return 0;
}



After I g++, I got the file a.out. But If I try to gcc, I still got the many error message.

What's the difference between g++ and gcc? If I assume g++ works in my case (as I can get the file a.out), what should I do next? To link? But how? It didn't specify in the tutorial?

Or is it possible I didn't set the gcc correct? (I just install the gcc and use it right away, didn't do anything else).

Enter ./a.out on the command line. Many (most?) distributions these days to not include the current directory on the PATH (it's a security issue). So you have to enter the "dot" to indicate current directory.


gcc and g++ are both part of the GNU compiler suite.

To put it in simplest terms, if you have a C source file called "something.c" then you can compile it with the following:

gcc something.c

If there are no errors, then the default output file name (the executable) is called a.out. There are command-line switches that you can use to cause other things to happen, but this is the simplest.

If you have a C++ source file called "something.cpp" then you can compile it with the following:

g++ something.cpp

f there are no errors, then the default output file name (the executable) is called a.out. There are command-line switches that you can use to cause other things to happen, but this is the simplest.

Regards,

Dave

gcc is the C compiler invocation method. g++ is the C++ compiler invocation method.

Use:

g++ -g -Wall -W -o executabe-name-that-you-want-to-use your-cpp-file.cpp

-g means to include debugging symbols in the build. These will be necessary when debugging your applications. Use gdb in order to debug your applications.

-Wall means to include all warnings.

-W means to include "extra" warnings. It has been replaced by -Wextra, but the "old" version -W is still supported.

-o filename means to output the result of compilation and linkage to the named filename. If not specified, a.out is used.


:davis:

Thank you SO MUCH for the excellent guidance. I hope I can learn more from you in the future.