C++ หาค่า PI ที่มีค่าเท่ากับ 3.141592xxx ว่ามีทั้งหมดกี่พจน์

int i = 2, j = 3, n = 1;
double target = 3.141592;
double result_neg = 1.0, result_pos = 1.0, result_all = 4.0;

while (n <= 3'000'000)
{
if (i - j == -1)
{
cout << fixed;
result_neg = (double)i / j;
result_all =  result_all * result_neg;
i += 2;
n++;
if (abs(target - result_all) <= 0.0000000001)
{
break;
}
}
if (i - j == 1)
{
cout << fixed;
result_pos = (double)i / j;
result_all =  result_all * result_pos;
j += 2;
n++;
if (abs(target - result_all) <= 0.0000000001)
{
break;
}
}
}
cout << setprecision(9);
cout<< result_all << endl;
cout <<endl<< n-1 << endl;