C语言循环经典例题

1.提示用户输入一个数n，打印出1~n的所有偶数平方值

int main()
{
	int n = 0;
	int i = 2;
	printf("input a number:n");
	scanf_s("%d", &n);
	while (i * i <= n)
	{
		printf("%d n", i * i);
		i += 2;
	}
	printf("n");
	return 0;
}

2.一球从100米高度自由落下，每次落地后反跳回原高度的一般，再落下时，求它在第10次落地时，共经过多少米》第10次反弹多高？

int main()
{
	double sn = 100;
	double hn = sn / 2;
	for (int i = 2; i <= 10; ++i)
	{
		sn = sn + 2 * hn;
		hn = hn / 2;
	}
	printf("total:%fn", sn);
	printf("第10次弹的高度:%fn", hn);
	return 0;
}

3.求黄金分割比

#define N 30
int main()
{
	int ar[N] = { 1,1 };
	for (int i = 2; i < N; ++i)
	{
		ar[i] = ar[i - 1] + ar[i - 2];
	}
	for (int i = 3; i < N - 1; ++i)
	{
		printf("%d / %d => %2.10lf n", ar[i], ar[i + 1], ar[i] / ar[i + 1]);

	}
	return 0;
}

4.牛顿迭代法求开放`

double my_sqrt(double a)
{
	double x0 = a / 2;
	double x1 = (x0 + a / x0) / 2;

	while (x0 - x1 > 0.000001)
	{
		x0 = x1;
		x1 = (x0 + a / x0) / 2;
	}
	return x1;
}

int main()
{
	double x, a;
	scanf("%lf", &a);
	x = my_sqrt(a);
	printf("x = %lfn", x);//精度控制
	return 0;
}

5.完数，求出完数，并输出因子

int main()
{
	int n = 1000;
	for (int i = 3; i <= 1000; ++i)
	{
		int sum = 0;
		for (int j = 1; j < i / 2 + 1; ++j)
		{
			if (i % j == 0)
			{
				sum = sum + j;
			}
		}
		if (sum == i)
		{
			printf("%d =>  ", i);
			for (int j = 1; j < i / 2 + 1; ++j)
			{
				if (i % j == 0)
				{
					printf("%d ", j);
				}
			}
			printf("n");
		}
	}
	return 0;
}