c语言编写函数求1/2+2/3+3/5+5/8+…前n项之和

#include <stdio.h>

double sum(int n) {
double a = 1, b = 2, c = 0, s = 0;
int i;
for (i = 1; i <= n; i++) {
s += a / b;
c = a + b;
a = b;
b = c;
}
return s;
}

int main() {
int n;
printf("请输入n：");
scanf("%d", &n);
printf("前%d项之和为：%.6lf", n, sum(n));
return 0;
}