C++ primer plus第六版课后编程练习答案：6.5

#define  _CRT_SECURE_NO_WARNINGS 
#include 
#include
#include
using namespace std;

const double tax_in_5000=0;
const double tax_5001_to_15000=0.10;
const double tax_15001_to_35000 = 0.15;
const double tax_beyond_35000 = 0.20;

int main()
{
    int income;
    double tax;

    cout << "Please enter your income: ";
    while (cin >> income)
    {
        if (income < 0)
            break;
        else if (income <= 5000)
            tax = income*tax_in_5000;
        else if (income>5000 && income <= 15000)
            tax = 5000 * tax_in_5000 + (income - 5000)*tax_5001_to_15000;
        else if (income > 15000 && income <= 35000)
            tax = 5000 * tax_in_5000 + 10000 * tax_5001_to_15000 + (income - 15000)*tax_15001_to_35000;
        else
            tax = 5000 * tax_in_5000 + 10000 * tax_5001_to_15000 + 20000 * tax_15001_to_35000 + (income - 35000)*tax_beyond_35000;
        cout << "Yout tax is: " << tax <<" tvraps."<< endl;
        cout << "Please enter your income: ";
    }
    cout << "Bye!" << endl;

}