/in/foo.c: In function 'main':
/in/foo.c:7:10: warning: format '%f' expects argument of type 'float *', but argument 2 has type 'double' [-Wformat=]
  scanf("%f",x);
          ^
/in/foo.c:6:8: warning: variable 'y' set but not used [-Wunused-but-set-variable]
  float y;
        ^
/in/foo.c:7:2: warning: 'x' is used uninitialized in this function [-Wuninitialized]
  scanf("%f",x);
  ^~~~~~~~~~~~~