Starting debugger: W:\gdb2018-07-25-bundle-python27\bin\gdb.exe -nx -fullname -quiet W:\R-3.5._\App\R-Portable\bin\i386\Rgui.exe -args W:/R-3.5._/codeblocksMeta/CodeBlocks/gdbCgen/bin/Debug/gdbCgen.exe
I think you use the wrong command.
here, you want to use GDB.exe to debug the "Rgui.exe". "gdbCgen.exe" is an argument passed to the start command of the "Rgui.exe".
Normally, you try first try this in Windows Command line, such as:
gdb.exe -nx -fullname -quiet -args W:\R-3.5._\App\R-Portable\bin\i386\Rgui.exe
After that, you can set the args:
set args W:/R-3.5._/codeblocksMeta/CodeBlocks/gdbCgen/bin/Debug/gdbCgen.exe
Finally, you can type:
To start the debugging.
Under C::B's debugger plugin, you use the same way, the command line arguments are set in "Menu->Project->Set program argument..."
EDIT: Please enable the "Full Debug log" in your C::B's debugger plugin settings to show the full debug log.