c++作业3

#include <iostream.h>
void main()
{
int year,month;
cout<<"请输入年份和月份："<<endl;
cin>>year>>month;
if(month==2)
{
if(year%4==0&&year%100!=0||year%400==0)
cout<<month<<"月的天数为29天"<<endl;
else
cout<<month<<"月的天数为28天"<<endl;
}
else
if(month==4||month==6||month==9||month==11)
cout<<month<<"月的天数为30天"<<endl;
else
cout<<month<<"月的天数为31天"<<endl;
}

#include<iostream.h>
void main()
{
int a;
double b, Dmoney,Dinterest,Dyear,Drate;
cout<<"欢迎使用利息计算器!"<<'\n';
cout<<"请输入存款金额：";
cin>>Dmoney;
cout<<"=====存款期限====="<<'\n'<<"1.3个月"<<'\n'<<"2.6个月"<<'\n'<<"3.一年"<<'\n'<<"4.二年"<<'\n'<<"5.三年"<<'\n'<<"6.六年"<<endl;
cout<<"请输入存款期限的代码:";
cin>>a;
switch(a)
{
case 1:Dyear=0.25;Drate=0.031;break;
case 2:Dyear=0.5;Drate=0.033;break;
case 3:Dyear=1;Drate=0.035;break;
case 4:Dyear=2;Drate=0.044;break;
case 5:Dyear=3;Drate=0.05;break;
case 6:Dyear=6;Drate=0.055;break;
default:cout<<"代码错误!"<<endl;
}
Dinterest=Dmoney*Dyear*Drate;
b=Dinterest+Dmoney;
cout<<"到期利息为："<<Dinterest<<"元，本息合计共"<<b<<"元"<<'\n';
cout<<"感谢您的使用，欢迎下次光临"<<endl;
}

#include<iostream.h>
#include<cmath>
void main()
{
double x,y;
cout<<"请输入x=";
cin>>x;
if(x>=10)
y=1/(x+1);
else if(x>=6)
y=sqrt(x+1);
else if(x>=2)
y=(x*x)+1;
else
y=x;
cout<<"y="<<y;
}