The C and C++ compilers are integrated; G++ is a script to call Gcc with options to recognize C++.
Gcc processes input files through one or more stages.

In general G++ program.cpp or G++ program.c will cause the Gcc to create an executable file as a.out.
This file can be run to produce the output from the program.  The G++ command on some machines is 
replaced with cc.  In either case, the G++ or cc command will call the Gcc compiler.