C++作业3

#include<iostream>
using namespace std;
int main()
{
double dSalary,dTax,n;
cout<<"请输入您本月的收入总额（元）：  ";
cin>>dSalary;
n=dSalary-3500;
if(n<=0)
dTax=0;
else if (0<n&&n<=1500)
dTax=0.03*n;
else if(1500<n&&n<=4500)
dTax=0.1*n-105;
else if(4500<n&&n<=9000)
dTax=0.2*n-555;
else if(9000<n&&n<=35000)
dTax=0.25*n-1005;
else if(35000<n&&n<=55000)
dTax=0.3*n-2755;
else if(55000<n&&n<=80000)
dTax=0.35*n-5505;
else
dTax=0.45*n-13505;
cout<<"您本月应缴个人所得税(元):   "<<dTax<<endl;
cout<<"您税后收入是(元):   "<<dSalary-dTax<<endl;
cout<<"依法纳税，共享繁荣。谢谢使用!"<<endl;
}

#include<iostream>
using namespace std;
int main()
{
int year,month,day,a;
cout<<"请输入年月"<<endl;
cin>>year>>month;
if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
day=31;
else if(month==4||month==6||month==9||month==11)
day=30;
else if(year%4==0&&year%100!=0||year%400==0&&month==2)
day=29;
else day=28;
cout<<"这个月有"<<day<<"天"<<endl;

}

#include<iostream>
#include<math.h>
using namespace std;
int main()
{
double x,y;
cout<<"请输入x的值： ";
cin>>x;
if(x<2)
y=x;
else if(2<=x&&x<6)
y=x*x+1;
else if(6<=x&&x<10)
y=sqrt(x+1);
else
y=1/(1+x);
cout<<"y的值为："<<y<<endl;
}