5.+编程实现：求序列2/1+3/2+5/3+8/5+…前20项之和

是两种编程语言实现序列2/1+3/2+5/3+8/5+…前20项之和的代码：

C语言实现：

#include <stdio.h>

int main() {
    float top = 2, base = 1;
    float t, sum = 0;
    int times = 0;
    while (times++ < 20) {
        sum += top / base;
        t = base;
        base = top;
        top += t;
    }
    printf("前20项和为：%f\n", sum);
    return 0;
}

Java语言实现：

public class Main {
    public static void main(String[] args) {
        double a = 2.0;
        double b = 1.0;
        double num;
        double sum = 0.0;
        for (int i = 1; i <= 20; i++) {
            num = a / b;
            sum += num;
            a = a + b;
            b = a - b;
        }
        System.out.println("前20项和为：" + sum);
    }
}