为什么代码答案不对

Question

#include<stdio.h>#include<math.h>int main(){ double i,n,sum,eps,term; scanf("%lf",&eps); sum=0; i=1; n=1; do{ sum=sum+term; n=-n; i=i+3; term=n/i; }while(fabs(term)>eps); printf("%f",sum);}本题要求编写程序，计算序列部分和 1 - 1/4 + 1/7 - 1/10 + ... 直到最后一项的绝对值不大于给定精度eps

Answer 1

#include<stdio.h>
#include<math.h>
main()
{int n;
double sum=0,esp;
scanf("%lf",&esp);
for(n=1;;n++)
{
sum=sum+pow(-1,n+1)*1.0/(3*n-2);
if(1.0/(3*n-2)<=esp)
break;
}
printf("sum=%.6f",sum);}

Answer 2

term没有赋初值1