/in/foo.cc: In constructor 'data::data(int, double, double, double)':
/in/foo.cc:9:26: warning: 'data::id' will be initialized after [-Wreorder]
  double x,y,a,b,r,k; int id;
                          ^~
/in/foo.cc:9:13: warning:   'double data::a' [-Wreorder]
  double x,y,a,b,r,k; int id;
             ^
/in/foo.cc:11:2: warning:   when initialized here [-Wreorder]
  data(int I,double A,double B,double R):id(I),a(A),b(B),r(R){k=-A/B;}
  ^~~~