c++第三次作业

#include <iostream>
using namespace std;
int main( )
{
int year,month;
cout<<"请输入年份和月份";
cin>>year>>month;
if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
cout<<"本月有31天";
else if(year%400==0||year%4==0&&year%100!=0&&month==2)
cout<<"本月有29天";
else if(month==2)
cout<<"本月有28天";
else if(month==4||month==6||month==9||month==11)
cout<<"本月有30天";
return 0;
}

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

#include<iostream>
#include<cmath>
using namespace std;
int main( )
{
int money,a,b,c;
cout<<"欢迎使用利息计算器!"<<endl;
cout<<"请输入存款金额:"<<endl;
cin>>money;
cout<<"=====存款期限======="<<endl;
cout<<"1.3个月"<<endl;
cout<<"2.6个月"<<endl;
cout<<"3.一年"<<endl;
cout<<"4.两年"<<endl;
cout<<"5.三年"<<endl;
cout<<"6.五年"<<endl;
cout<<"请输入存款期限的代号:"<<endl;
cin>>a;
switch(a)
{
double b,c;
case 1:b=money*0.031*0.25; c=b+money;cout<<"到期利息为:"<<b<<","<<"本息合计共"<<c<<"元"<<endl;break;
case 2:b=money*0.033*0.5; c=b+money;cout<<"到期利息为:"<<b<<","<<"本息合计共"<<c<<"元"<<endl;break;
case 3:b=money*0.035*1; c=b+money;cout<<"到期利息为:"<<b<<","<<"本息合计共"<<c<<"元"<<endl;break;
case 4:b=money*0.044*2; c=b+money;cout<<"到期利息为:"<<b<<","<<"本息合计共"<<c<<"元"<<endl;break;
case 5:b=money*0.05*3; c=b+money;cout<<"到期利息为:"<<b<<","<<"本息合计共"<<c<<"元"<<endl;break;
case 6:b=money*0.055*5; c=b+money;cout<<"到期利息为:"<<b<<","<<"本息合计共"<<c<<"元"<<endl;break;
}
cout<<"感谢您的使用，欢迎下次光临!"<<endl;
return 0;
}