C语言的编程，求一远两次方程的根

int f (double a, double b, double c, double& x1, double& x2)
{
if (a == 0)
return 1; // 不是一元二次方程
else
{
double delta = b*b-4*a*c;
if (delta < 0)
return 2; //无解
else
{
x1 = (-b-sqrt(delta))/2;
x2 = (-b＋sqrt(delta))/2;
return 0; //有解
}
}
}