#include <stdio.h>
#include <stdlib.h>
void main()
{
	int i, n;
	double num = 0.0, sum = 0.0;
	for (i = 1; i <= 100;i++ )
	{   if (i%2==0)
		n = -1;
	    else
	    n = 1;
		num = n*1.0 / i;
		sum = sum + num;
	}
	printf("结果为%f\n", sum);
	system("pause");
}