函数的功能是计算并输出该数列前n项的平方根之和sum

#include <stdio.h>
#include <math.h>
/************found************/
fun(int n)//fun函数的定义根据题干要返回前n项的平方根之和，函数具有返回值，所以“fun(int n)”应改为“double fun(int n)”，double为双精度型变量。
{double sum, s0, s1, s2, s; int k;
   sum = 1.0;
   if (n <= 2) sum = 0.0;
   s0 = 0.0; s1 = 0.0; s2 = 1.0;
   for (k = 4; k <= n; k++)
   {s = s0 + s1 + s2;
      sum += sqrt(s);
      s0 = s1; s1 = s2; s2 = s;
   }
/************found************/
   return sum//C语言语法每一句C语言后面应该以“;”为结尾
}
main ()
{int n;
   printf("Input N=");
   scanf("%d", &n);
   printf("%f\n", fun(n));
}