5.3 数组初始化

#include<iostream>
#include<cstdio>
int main()
{
	int n;
	scanf("%d", &n);
	switch(n)
	{
		case 1://如果n==1 
			printf("Monday.");//输出Monday 
			break;//跳出整个switch循环 
		case 2:
			printf("Tuesday.");
			break;
		case 3:
			printf("Wednesday.");
			break;
		case 4:
			printf("Thursday.");
			break;
		case 5:
			printf("Friday.");
			break;
		case 6:
			printf("Saturday.");
			break;
		case 7:
			printf("Sunday.");
			break;
		default:
			printf("Illegal.");
	}
	return 0;
}

#include<iostream>
#include<cstring>
using namespace std;
string weekdays[]={"Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"};
int main()
{
	int n;
	cin >> n;
	if(n < 1 || n > 7)
		cout << "Illegal";
	else
		cout << weekdays[n-1];
	return 0;
} 

#include<iostream>
using namespace std;
int monthdays[13]={-1,31,28,31,30,31,30,31,31,30,31,30,31};
int main()
{
	int year, month, day, days=0;
	cin >> year >> month >> day;
	for(int i = 2012; i < year; ++i)//算年一共有多少天 
	{
		if((i % 4 == 0 && i % 100 != 0) || i % 400 == 0)
			days += 366;
		else 
			days += 365;
	}
	if((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
			monthdays[2] = 29;
	for(int i = 1; i < month; ++i)//算不足一年的有几个月所有的天数 
	{
		days += monthdays[i];
	} 
	days += day;//算剩余的最后一个月的天数 
	days -= 22;//减去第一年1月份的天数 
	cout << days % 7 << endl;//用总的天数对7取余，就可以得到星期几了 
	return 0;
}