输入任意n值，求1-1/2+2/3-3/4+…±( n-1)/n

Question

输入任意n值，求1-1/2+2/3-3/4+…±( n-1)/n

Answer 1

#include<stdio.h>
int main()
{
    double a=1,b=0,i,sum=0,n,k=1;
    printf("请输入n:");
    scanf("%lf",&n);
    for(i=2;i<=n;i++)
    {
        a=a+1;
        b=b+1;
        k=-k;
        sum=sum+k*(b/a);
    }
    printf("1-1/2+2/3-3/4...(n-1)/n =：");
    printf("%lf",sum);
    return 0;
}