用Java分别用do+while和for循环计算1+1/2!+1/3!+1/4!+...的前20项之和 的代码

以下是Java分别使用do-while和for循环计算1+1/2!+1/3!+1/!+...的前20项之和的代码：

1. 使用do-while循环：

public class Example1_3 {
    public static void main(String args[]) {
        double a = 1, b = 1, c = 0;
        System.out.println("do-while循环:");
        do {
            c = b + c;
            a++;
            b = (1.0 / a) * b;
        } while (a <= 20);
        System.out.println(" " + c);
    }
}

2. 使用for循环：

public class Example1_3 {
    public static void main(String args[]) {
        double a, b, c;
        System.out.println("for循环:");
        for (c = 0, b = 1, a = 1; a <= 20; a++) {
            b *= (1.0 / a);
            c += b;
        }
        System.out.println(" " + c);
    }
}