编写C语言程序:输入一个正整数n,求S=1-1/2+2/3-3/5+5/8-8/13+···的前n项之和。
#include <stdio.h>
int main()
{
int n,i,a,b;
double sum;
scanf("%d",&n);
for(i=0,a=b=1,sum=0;i<n;++i)
sum+=(double)a/b*(i%2?-1:1);
b=a+b;
a=b-a;
}
printf("%lf",sum);
return 0;