Java经典编程习题100例：第9例：计算圆周率

PI＝4－4/3+4/5-4/7.......
打印出第一个大于3.1415小于3.1416的值

public class Main {
    public static void main(String[] args) {
        double pi = 4;
        double temp = 0;
        int flag = -1;
        for (int i = 3; i <= 100000000; i += 2) {
            temp = 4.0 / i;
            pi = pi + flag * temp;
            flag = -1*flag;
            if (pi > 3.1415 && pi < 3.1416) {
                System.out.println("pi=" + pi);
                break;
            }
        }
    }
}