Leonardo's blog

Did you know that you can use Lazarus to debug applications compiled with other languages than Pascal?. If not, I can tell you that yes, you can!.

Some times, I need to connect Delphi/FPC applications to C or C++ shared libraries compiled with gcc or g++, but its a pain to debug using command line gdb.

Lazarus to the rescue

One very interesting way to debug C++ code I use is to open one or more C++ source files in Lazarus, set breakpoints, then configure the host application and run. Magically the execution stops in the breakpoints I defined, and I can step and inspect symbols as I do usually on my Lazarus applications.

An example

I have a Delphi application that relies on a C++ Dll compiled with g++ (using the -g parameter to include debug information). Using Delphi, I can debug until the point an external function is called, but nothing further than that.

To be able to debug the dll source code, you can just follow this steps in Lazarus:

1) Project -> New -> Application.
2) File -> Open -> your_cpp_file
3) Define as many breakpoints (F5) as you need.
4) Run -> Run parameters -> Host application: c:\myapp\myapp.exe
5) Run -> Run parameters -> Working directory: c:\myapp

That's all, now just click on run (F9). This will open the host application, and when it calls the dll, the breakpoints you configured will be reached.