C语言：计算1/1-1/2+1/3-1/4+1/5 …… + 1/99 - 1/100 的值

#include<stdlib.h>
#include<stdio.h>

void sum()
{
double a = 1.0;  //分母
double sum = 1.0 / a;
int i = 2;
for (; i <= 100; i++)
{
if (i % 2 == 0)
{
sum -= 1.0 / i;
}
else
{
sum += 1.0 / i;
}
}
printf("%lf    ", sum);
}

int main()
{
sum();
system("pause");
return 0;
}