C++作業三

一:今月は何日ですか

#include<iostream>
int main()
{
	int year,month,day;
	std::cout<<"  year month    ：year?month?"<<"
";
	std::cin>>year>>month;
	switch(month)
	{
	case 1:
	case 3:
	case 5:
	case 7:
	case 8:
	case 10:
	case 12:day=31;
		break;
	case 4:
    case 6:
	case 9:
	case 11:day=30;
		break;
	case 2: if (year%4==0&&year%100!=0||year%400==0)
				day=29;
		else
			day=28;
		break;
	default:day=0;
	}
	if(day==0)
		std::cout<<"    1~12  "<<"
";
	else
		std::cout<<year<<" "<<month<<"  "<<day<<" "<<"
";
	return 0;
}

2:
定期預金利息計算機

#include<iostream>
int main()
{
	int daihao;
	double money,interest;
	std::cout<<"       :";
	std::cin>>money;
	std::cout<<"========    ==========="<<"
";
	std::cout<<"1.3  "<<"
";
	std::cout<<"2.6  "<<"
";
	std::cout<<"3.  "<<"
";
	std::cout<<"4.  "<<"
";
	std::cout<<"5.  "<<"
";
	std::cout<<"6.  "<<"
";
	std::cout<<"         "<<"
";
	std::cin>>daihao;
	switch(daihao)
	{
	case 1:interest=money*0.25*0.031;break;
	case 2:interest=money*0.5*0.033;break;
	case 3:interest=money*1*0.035;break;
	case 4:interest=money*2*0.044;break;
	case 5:interest=money*3*0.05;break;
	case 6:interest=money*5*0.056;break;
	default:interest=0;
	}
	if(interest==0)
		std::cout<<"       "<<"
";
	else
	{
		std::cout<<"     :"<<interest<<"
";
		std::cout<<"    ："<<money+interest<<"
";
		std::cout<<"      ，      。"<<"
";
	}
	return 0;
}

3:
マルチセグメント関数の評価

#include<iostream>
#include<cmath>
int main()
{
	int x,z;
	double y;
	std::cout<<"       。";
	std::cin>>x;
	if(x<2)
		std::cout<<"y="<<x<<"
";
	else if(x>=2&&x<6)
		std::cout<<"y="<<x*x+1<<"
";
	else if(x>=6&&x<10)
		std::cout<<"y="<<sqrt(x+1)<<"
";
	else if(x>=10)
		std::cout<<"y="<<1/double(x+1)<<"
";
	return 0;
}

四:心得
ifとswitch文の役割は大きく、多く使用できます.
五:知識点のまとめ
各case文の後はbreak文で終わり、
各switch文にはdefault文が含まれており、ループが正常であることを保証します.
強制変換で自分の望む値を得ることができます.