【输入某年某日，判断这是这一年的第几天】

for语句和switch语句分别实现

文章目录

前言

一、用switch做

二、用for循环做

​编辑

总结

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前言

用两种不同的方法求解【输入某年某日，判断这是这一年的第几天】

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一、用switch做

代码如下（示例）：

int main()
{
	int y, m, d, count, k;
	scanf("%d %d %d", &y, &m, &d);
	if ((y % 4 == 0 && y % 100 != 0) || y % 400 == 0)
		k = 1;
	else k = 0;
	count = d;
	switch (m - 1)
	{
	case 11:count = count + 30;
	case 10:count = count + 31;
	case 9:count = count + 30;
	case 8:count = count + 31;
	case 7:count = count + 31;
	case 6:count = count + 30;
	case 5:count = count + 31;
	case 4:count = count + 30;
	case 3:count = count + 31;
	case 2:count = count + 28+k;
	case 1:count = count + 31;
	}
	printf("%d年%d月%d日是%d年的第%d天", y, m, d, y, count);
	return 0;
}

该处不能把count=d放在switch里面，switch语句执行时会先匹配case，若放在switch语句里面，会报错，出现未初始化变量count

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如下代码及运行结果：

二、用for循环做

代码如下（示例）：

int main()
{
	int i,y, m, d, countday, k;
	int mouth[12] = { 0,31,28,31,30,31,30,31,31,30,31,30 };
	scanf("%d %d %d", &y, &m, &d);
	if ((y % 4 == 0 & y % 10 != 0) || y % 400 == 0)
		k = 1;
	else k = 0;
	mouth[2] = mouth[2] + k;
	countday = d;
	for (i = 1; i < m; i++)
		countday = countday + mouth[i];
	printf("%d年%d月%d日是%d年的第%d天", y, m, d, y, countday);
	return 0;
}

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如下代码及运行结果： 

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总结