/in/foo.cc: In function 'int main()':
/in/foo.cc:5:11: warning: unused variable 'a' [-Wunused-variable]
  double z,a=0,b=0,c=0,d=0;
           ^
/in/foo.cc:5:15: warning: unused variable 'b' [-Wunused-variable]
  double z,a=0,b=0,c=0,d=0;
               ^
/in/foo.cc:5:19: warning: unused variable 'c' [-Wunused-variable]
  double z,a=0,b=0,c=0,d=0;
                   ^
/in/foo.cc:5:23: warning: unused variable 'd' [-Wunused-variable]
  double z,a=0,b=0,c=0,d=0;
                       ^