Question

I’m trying to get Eclipse CDT (64 bit eclipse) working on Windows 7 with GCC. When I first got GDB working (that was a challenge in itself), running the program in debug mode was the only way I got output. Running it normally didn’t give any console output. After hours of googling, I figured out that if I added C:/cygwin/bin to my environment path in eclipse, I could get output when running the program normally. Then I ran it in debug mode and there was no output. I tested this a couple of times to make sure it was the addition of the path causing the problem. This is the program I was running,

#include <iostream>

using namespace std;

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

So how can I get both normal and debug modes working, and why did I have to include that path in the first place (it’s already in my cygwin path and why does CDT need it?) ? Also, why is it that if I add a path to my Run configurations it will also be added to my Debug configurations?

Answer 1

I don’t think I can answer everything but I use exactly the same set-up as you and I’ve had to deal with quite a few issues like this (I’m wondering if you had trouble how to juggle using the 32-bit/64-bit JVM and Internet browsing)!

The cygwin/bin path must be specified because that is where gcc, gdb and all the other cygwin tools and dlls are located (I’ll assume you’re using cygwin flavour of gcc rather than MinGW flavour). I believe you must specify it in the Windows environment (using a win32 file path) because Eclipse is running using the Windows JVM and therefore deals with win32 paths. Consequently, it doesn’t matter that cygwin/bin is added to the PATH variable in the cygwin environment. CDT is looking for cygwin using Eclipse, and Eclipse needs to find cygwin1.dll from Windows.

I might be totally wrong, but if I had to guess I would say that you need to make absolutely sure you have properly set the PATH environment variable correctly for both configurations.

One thing to note is that in Eclipse there is no difference between a configuration shown in the Debug Configurations window and one with the same name in the Run Configurations window. The only difference between the two windows is that one will run the program without using a debugger and has tabs for setting debug settings. Therefore it’s no surprise that changing settings in one will also affect the other.

As you may know, for many projects the build system is set up to produce two (sometimes more) sets of binaries: one with debugging info/symbols (DEBUG) and one without (RELEASE). In this case, you normally have two configurations in Eclipse: one to run the DEBUG binary and one to run the RELEASE binary. Both of these will show up in both the Debug Configurations window and in the Run Configurations window. The point is that you can run DEBUG either with or without gdb, but RELEASE cannot be used by gdb.

That said, I’m not sure why adding the correct path to the run configuration would stop the DEBUG binary from outputting to the console. I suspect something else is going on here, perhaps a mismatch of debug info and debugger.

To (hopefully) answer your question as to how to get both configurations working, go the whole-hog and just add C:\cygwin\bin; to the Windows PATH environment variable. I’m guessing that will allow both to work. I’ll assume you know how to do that but please post a comment if not.

The other thing to try would be to compile and run the program from a cygwin shell. If it works there it’s probably a safe bet that your PATH environment variable is not set correctly when using eclipse.

Hope that helps!