c语言斐波那契数列求前n项和

以下是C语言求斐波那契数列前n项和的代码：

#include <stdio.h>

int fbi(int n) // 求斐波那契数列第n项的值
{
    if (n == 1 || n == 2)
        return 1;
    else
        return fbi(n - 1) + fbi(n - 2);
}

int sum_fbi(int x) // 求斐波那契数列前x项的和
{
    if (x <= 0)
        return 0;
    int s = 0;
    for (int i = 1; i <= x; i++)
    {
        s += fbi(i);
    }
    return s;
}

int main()
{
    int x = 6;
    printf("斐波那契数列前15项为:");
    for (int i = 1; i <= 15; i++)
    {
        printf(" %d ", fbi(i));
    }
    printf("\n");
    printf("斐波那契数列前%d项和为%d", x, sum_fbi(x));
    return 0;
}