设计一个函数my_sum(n)，求 1/2−2/3+3/5−5/8+8/13−… 的前n项的和 c语言

以下是C语言实现的my_sum函数，用于求解1/2−2/3+3/5−5/8+8/13−…的前n项和：

#include <stdio.h>

double my_sum(int n) {
    double sum = 0.0;
    double a = 1.0, b = 2.0, c;
    int i;
 for (i = 1; i <= n; i++) {
        sum += a / b;
        c = a + b        a = b;
        b = c;
        if (i % 2 == 0) {
            sum -= a / b;
            c = a + b;
            a = b;
            b = c;
        }
    }
    return sum;
}

int main() {
    int n = 6;
    printf("前%d项和为：%lf\n", n, my_sum(n));
    return 0;
}