/in/foo.c: In function 'main':
/in/foo.c:10:12: warning: format '%d' expects argument of type 'int', but argument 2 has type 'double' [-Wformat=]
   printf("%d",(-b)/c);
            ^
/in/foo.c:28:24: error: 'i' undeclared (first use in this function)
   x1=(-b+sqrt(-delta))*i/(2*a);
                        ^
/in/foo.c:28:24: note: each undeclared identifier is reported only once for each function it appears in