while循环

计算(1-1/3+1/5-1/7+1/9-1/11…) * 4

#include<stdio.h>
int main(void)
{
	int i=1;
	int j=1;
	double sum=0; // 结果肯定小数，所以要定义成double或者float型
	while(1.0/i > 1e-6)
	{
		sum = sum + (1.0 / i) * j;
		i = i + 2;
		j = -j;
	}
	sum = sum * 4;
	printf("sum = %1f\n", sum);
	return 0;
}

用while循环写 1+2+3+4+ … + 100