C++ hello world on Linux - linux

Question

Under Windows I installed MinGW and Eclipse, and created a new C++ project with the inspiring name of foo, using the MinGW GCC toolchain, and this compiles, runs and even debugs. Wonderful.
Still under Windows, I installed Cygwin, an epic undertaking that stressed my internet connection. Eventually I specified Cygwin GCC toolchain and a projectname of bar. This compiles and runs but can't do step through debugging (claims it can't find source).
Under Linux, mint13 specifically, I installed the all-singing all-dancing C++ edition of Eclipse with all the trimmings and created a new C++ project, with the even more inspiring name of baz and the Linux GCC toolchain selected. Eclipse complains that it cannot find iostream.
I am rather confused by this. If I launch a terminal window and run g++ it is found, so clearly I have at least some of the GNU C++ stuff. I don't know what is missing. Linux is a new world for me. Can anyone offer guidance?
For the record, the generated code is in a file called foo.cpp (or bar.cpp according to project name) and looks like this:
#include <iostream>
using namespace std;
int main() {
cout << "Hello World" << endl; // prints Hello World
return 0;
}
#bmargulies - I know your comment was tongue in cheek but I wouldn't use emacs in a pink fit. I'd set up SAMBA and use Textpad on a Windows workstation because I have enough to learn without unnecessarily learning to use a new text editor. The reason I chose Eclipse was a vain hope that it might provide a working baseline with an integrated debugger from which to explore the brave new world of C++ on Linux. Combined with MinGW it did provide that on Windows.
I know the big problem here is not the tools, it is my ignorance and a set of expectations from a different world. This is compounded by a lack of experience with C++ - my sole experience with C++ was using TurboC fifteen years ago.
A source of great confusion is the mechanism used to resolve library references.
A lot of projects seem to use make, which as far as I can tell is a sort of script file for compiling and linking a project or set of projects. Make seems to come in a variety of flavours and there also seem to be alternatives that use makefile as well as alternatives that don't.
[expletive] what a mess.
#Basile - I am not wedded to the use of Eclipse, and I am well aware of the benefits of scripts over point and click use of IDE configuration (not least among which is that you can source-control the build process). I thank you for your reading list. Perhaps this is a silly (or premature) question but I have to ask: without an IDE like Eclipse that integrates an editor with a build tool, is it possible to do step-through debugging?
#bmargulies - I agree with you that there's probably something wrong with the toolchain definition but I lack the background and experience to conduct a meaningful investigation of that. As mentioned above, I had varying levels of success with different toolchains under Windows, so it is reasonable to conclude that the toolchain is a significant factor in the problem. Alas, I can't choose a MinGW toolchain under Linux.
Following Norm's advice I was able to compile foo.cpp from a command line. The hello world program executes with the desired behaviour, but I still don't know how g++ knew how to resolve iostream when the fancy IDE tool didn't.
Added a few more lines of code to foo and compiled it, to try out gdb. It works! Whoever would have imagined you could do step-through debugging with a teminal window! It's a bit clumsy though.
While Basile is clearly correct that a fancy IDE is not necessary, that's a bit like saying that I don't need my motorcycle because I can walk. I'll have a look at the other IDEs mentioned, but I suspect they will all make use of the same toolchains and therefore all be similarly afflicted by whatever I have misconfigured.
Basile, forgive me for moving the goalposts. My original goal was indeed "compile and run hello.cpp" but gdb was inevitably the next step. It works, and if this were the early 80s using a teletype at uni I would probably be pretty happy right now. But it's not the early eighties and I've spent the last decade with syntax-colouring, autocompletion, variable sniffing edit-and-continue debugging so (ungrateful sod that I am) now I want, well, everything!

Answer 1

I've used eclipse c/C++ version before and had a lot of the same problems. For me, eclipse was very difficult to work with. I would recommend using the command line to compile c/c++ programs to start with. Its easier and important to understand how executable are created, in my opinion.
g++ -Wall -g Hello.cpp -o Hello
will produce an executable Hello. -Wall is a option that gives you more warnings when you are compiling your programs. Some warnings will crash your program if you don't fix them so its nice to see them up front. -g gives you the debugging symbols so that gdb will be able to step through the program step by step.
When you do get into gdb by using gdb Hello you can check out this gdb cheatsheet.
Once you start writing programs with more than one source file you're going to need to understand the two main steps in compilation. The first step turns each individual source file into an object file. The next step links all the object files together to make an executable. This link might explain compiling and linking, obviously wikipedia is also a good source for that info.

Answer 2

You don't need a fancy IDE like Eclipse. The usual way of developing under Linux is to use several tools.
Use an editor like emacs or gedit to edit your helloworld.cpp file. Type emacs or gedit in your terminal to start the editor (possibly followed by helloworld.cpp i.e. the name of the edited file[s]).
Then, compile with the following command
g++ -Wall -g helloworld.cpp -o helloworld
that you type in your terminal. Improve your code till no warning is given. You might add -O after -g above if you want GCC to optimize (and -O2 or -O3 to optimize even more). You should ask GCC to optimize if you want to benchmark or release your binary executable program. Notice that g++ knows how to link the standard C++ library (libstdc++.so), and the headers are located in a standard location known to g++ (you could add a -v argument to g++ to make it show what is happenning). You'll need more arguments if you want to use additional libraries.
the order of arguments to g++ is important, particularly for -I options (include directories) and -l (libraries).
If you want to debug your program (avoid asking optimizations to GCC), type
gdb helloworld
which will run the debugger. Learn more about gdb (of course you can do step by step with gdb; you'll use the next, step, break, backtrace commands of gdb at first, and others -e.g. watch is very useful sometimes.)
If you want to run your program without a debugger, just type
./helloworld
Later, you'll want to develop a program in several compilation units. Learn to use a bulder like make for that. There are other builder programs, like omake and many others.
Read more about GCC (providing g++), Gnu Make, GDB (the gnu debugger), Emacs, GIT version control
I have configured my emacs to run make inside it by pressing the F12 key. You can compile under emacs if you want to.
For graphical user interface applications coded in C++, learn to use Qt.
PS. Linux is much more command line oriented that other systems. Believe us, this has incredible strengths. But it is a different way of working that on other systems, such as those sold by Microsoft.
PS. If you are fond of IDE, you could consider geany, anjuta, kate. However, few free software - coded in C or C++ - in a typical Linux distribution (Debian, Ubuntu, Fedora, ...) are built using these (or with Eclipse, which on Linux is often related to Java development). IMHO, this is significant.