程序代码：

# include <stdio.h>

int main(void)
{
    int i;
    double sum = 1, n = 1;
    for (i = 2; i <= 100; )
    {
        n = n * (-1);
        sum += n / i;
        i += 2;
    }
    printf("sum = %f",sum);
    return 0;
}