/in/foo.c: In function 'main':
/in/foo.c:12:2: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
  if(delter=0)
  ^~
/in/foo.c:27:23: warning: format '%lf' expects a matching 'double' argument [-Wformat=]
    printf("%.2lf\n%.2lf",x1);
                       ^