原题如下：考虑两个无线序列：
1.0＋1.0/2.0+1.0/3.0+1.0/4.0+……
1.0-1.0/2.0+1.0/3.0-1.0/4.0+……
编写一个程序来计算这两个序列不断变化的总和，直到达到某个次数。让用户交互地输入这个次数。
我自己编的程序如下所示：
#include <stdio.h>
int main(void)
{
    unsigned n, x, i;
    float sum1_n, sum2_n;
   
    while(1)
    {
        printf("请输入x的值：\n");
        i = scanf("%d", &x);
        if(i != 1)break;
        while(getchar() != '\n');
        sum1_n = 0;
        sum2_n = 0;
        
        if(x == 1)
        {
            sum1_n = 1;
            sum2_n = 1;
            printf("%f %f", sum1_n, sum2_n);
        }
        if(x == 2 * n)
        {
            for(n = 1; n <= x; n++)
            {
                sum2_n += 1 / (n-1) - 1 / n;
                sum1_n += 1 / n;
            }
            
            printf("%f %f", sum1_n, sum2_n);
        }
        else
        {
            for(n = 1; n <= x; n++)
            {
                sum2_n += 1 / n - 1 / (n - 1) + 1; // Thread1:EXC_ARITHMETIC(code=EXC_I386_DIV,subcode=0x0)[color=#FF0000]
                sum1_n += 1 / n;
            }
            printf("%f %f", sum1_n, sum2_n);
        }
        return 0;
    }
}

结果则如下所示
[local]1[/local]
输入任意结果都是显示错误，上方红字被提示有误，请示大神该如何修改呢？

#include <stdio.h>
int main(void)
{
    unsigned n, x, i;
    float sum1_n, sum2_n;
   
   
    while(1)
    {
        printf("请输入x的值：\n");
        i = scanf("%d", &x);
        if(i != 1)break;
        while(getchar() != '\n');
        sum1_n = 0;
        sum2_n = 0;
        
        if(x == 1)
        {
            sum1_n = 1;
            sum2_n = 1;
            printf("%f %f\n", sum1_n, sum2_n);
        }
        if(x % 2 == 0)
        {
            for(n = 2; n <= x; n++)
            {
                sum2_n += 1 / (n-1) - 1 / n;
                sum1_n += 1 / n;
            }
            
            printf("%f %f\n", sum1_n, sum2_n);
        }
        if((x % 2 == 1)&& (x != 1))
        {
            for(n = 2; n <= x; n++)
            {
                sum2_n += 1 / n - 1 / (n - 1) + 1;
                sum1_n += 1 / n;
            }
            printf("%f %f\n", sum1_n, sum2_n);
        }
        
    }
    return 0;
}
修改了下程序，然并软。

怎么算的－－我高数荒废了两年了哎