用函数求斐波那契数列前n项和

#include <stdio.h>

long fibonacci(int n) {

long num;

if (n == 1 || n == 2) {

num = 1;

} else {

num = fibonacci(n - 1) + fibonacci(n - 2);

}

return num;

}

int main () {

long sum = 0;

int n;

printf("请输入斐波那契数列的项数:");

scanf("%d", &n);

for (int i = 1; i <= n; i++) {

sum += fibonacci(i);

}

printf("斐波那契数列前%d项的和为%d。", n, sum);

return 0;

}