溢出原理

公式及推导
Avgi+1 = Avgi + (x - Avgi)/(i+1)
Avgi+1(i+1) = Avgi(i+1) + (x - Avgi)
左边Avgi+1*(i+1)表示i+1个第i+1时刻的平均值。
右边Avgi(i+1)表示i+1个第i时刻的平均值，(x - Avgi)表示第i+1时刻的平均值。
所以左边等于右边

源码及测试

double calc_avg(double avg, double val, int index)
{
	return avg + (val - avg)/index;
}

int main(int argc, char* argv[])
{
	 int data[4] = {0xFFFF0001, 0xFFFF0001, 0xFFFF0001, 0xFFFF0001};
	 int nAvg = (data[0]+data[1]+data[2]+data[3])/4;

	double dAvg = 0;
	for ( int i = 0; i < 4; i++ )
	{
		dAvg = calc_avg(dAvg, data[i], i+1);
	}
	int nTemp = dAvg;
	return 0;
}