Question

c++结果错误？

#include <iostream>using namespace std;class CPetrol{private:double amount90, amount93, amount98;double price90, price93, price98;double income90, income93, income98;public:void Setall(double,double,double);void Totallincome();void Showincome();};void CPetrol::Setall(double a,double b,double c){double price90 =a, price93 =b, price98 =c;}void CPetrol::Totallincome(){cout << "Please enter the amount of #90" << endl;cin >> amount90;income90 = amount90 * price90;cout << "Please enter the amount of #93" << endl;cin >> amount93;income93 = amount93 * price93;cout << "Please enter the amount of #98" << endl;cin >> amount98;income98 = amount98 * price98;}void CPetrol::Showincome(){cout << "The total income today is" << endl;double incomeall = income90 + income93 + income98;cout << incomeall << endl;}void main(){CPetrol petrol;petrol.Setall(3.96, 4.05, 4.38);petrol.Totallincome();petrol.Showincome();};

Answer 1

您好，你的问题，我之前好像也遇到过，以下是我原来的解决思路和方法，希望能帮助到你，若有错误，还望见谅！关键是printf默认总是设置小数点后精度为6，并且总是四舍五入输出结果，因此可以在funpi之后使用如下代码来输出：
pi -= 5 * y; //根据输出样例，要求直接舍去
printf("%.*f\n", n - 1, pi); //控制输出精度为n个有效数字，小数点前有一位非常感谢您的耐心观看，如有帮助请采纳，祝生活愉快！谢谢！

Answer 2

改这个地方，把double去掉