一元二次方程相关问题，求大佬解答？

Question

include

include

include

void f(double i, double j)
{
printf("i = ");
scanf_s("%d", &j);
}
int main(void)
{
double a = 0, b = 0, c = 0;
double A = 0, B = 0, C = 0;
double delta = 0;
double x1 = 0, x2 = 0;
char ch =0;
printf("请输入一元二次方程的三个系数： \n");
f(a, A);
f(b, B);
f(c, C);
delta = (b*b) - (4 * a * c);
do
{
if (delta > 0)
{
x1 = ((-b) + sqrt(delta)) / (2 * a);
x2 = ((-b) - sqrt(delta)) / (2 * a);
printf("该方程有两个解，x1 =%lf,x2=%lf\n", x1, x2);
}
else if (delta == 0)
{
x1 = x2 = (-b) / (2 * a);
printf("该方程有且只有一个解，x1 =x2 =%lf\n", x1);
}
else
printf("该方程没有实数解\n");
printf("请问是否需要继续（y/n）: \n");
scanf_s(" %c", ch);
} while ("ch = y" || "ch = Y");
system("pause");
return 0;
}

当在黑框中输入y时出现：缓冲区不等于nullptr? 请问这是什么意思啊
我这应该怎么改一下？

Answer 1

void f(double i, double j)
{
printf("i = ");
scanf_s("%d", &j);
}
->
void f(double* j)
{
scanf_s("%lf", j);
}
主程序
f(&a);
f(&b);
f(&c);