C Primer Plus9-10

/*10.编写并测试一个函数 Fibonacci()，在该函数中使用循环代替递归完成斐波纳契数列的计算。*/

#include<stdio.h>
#include<stdlib.h>

unsigned long Fibonacci (int );

int main(void)
 { 
     int n;

     printf("Enter an integer (q to quit):\n");

     while (scanf("%d", &n) == 1)
      {
            printf("The term %d of Fibonacci sequence is %lu\n", n, Fibonacci (n));
            printf("Enter an integer (q to quit):\n");
      }

     printf("Done.\n");

     system("pause");
     return 0;
 }

unsigned long Fibonacci (int n)
 {
    int n1,n2,temp,i;
    if(n >2)
    for(n1=1,n2=1,i=3; i<=n; i++)
   { 
     temp = n1 + n2;
     n1 = n2;
     n2 = temp;
    }   
   else n2=1;
   return n2;
}