Question

我遇到了这个程序的问题。当我编译它时，我根据用户输入初始化所有变量，但是cout仍然显示问题有＆＃39; 0＆＃39; 0对于大多数陈述而言，对于其中一个陈述而言，它是一个负面的陈述＆＃39;数。有什么想法吗？

#include <iostream>
#include <conio.h>
#include <cmath>
#include <stdexcept>

using namespace std;
class MortgageCalc
{
protected:
    float term;
public:
    void setData(float, float, float);
    float setTerm ();
    float monthly;
    float total;
    float interest;
    int years;
    float loan;
};

void MortgageCalc::setData(float l, float i, float y)
{
   loan = l;
   interest = i;
   years = y;
   setTerm();
}

float MortgageCalc::setTerm()
{  //simple interest calculation with power calc to establish whole number translation
     term = pow((1 + ((interest/100) / 12)), (12 * years));
     return term;
}

class mPayment : public MortgageCalc
{
public:
    int monthly()
    {
        return ((loan * ((interest/100) / 12) * term ) / (term - 1));
    }
};

class tPayment : public mPayment
{
public:
    int total()
    {
        return (monthly() * (years * 12));

    }
};

class iPayment : public tPayment
{
public:
    int plusInterest()
    {
        return (total() - loan);
    }
};

int main()
{
double loan(0), interest(0);
int years = 0;

MortgageCalc mort1;
    cout << "Enter the total loan amount on your mortgage loan: $";  //established loan variable
        cin >> loan;
    cout << "Enter the interest rate (in whole #'s only): ";  //establishes interest rate variable
        cin >> interest;
    cout << "Enter the length of the loan in years: "; //establishes term of payments
        cin >> years;
mort1.setData(loan, interest, years);

mPayment m;
       cout << "Monthly payment due is " << m.monthly() << "." << endl;

tPayment t;
        cout << "Total payment will be " << t.total() << "." << endl;

iPayment i;
        cout << "Total payment plus Interest will be " << i.plusInterest() << "." << endl;

return 0;
};

Answer 1

您在这些行上使用默认构造函数：

mPayment m;
tPayment t;
iPayment i;

他们对mort1中保留的先前输入数据没有概念。你没有注意任何方式分享＆＃34;分享＆＃34;或＆＃34;沟通＆＃34;这个数据。

m，t，i都是使用随机数据初始化的。与mort1无关。

我不会详细了解这里的正确架构，但是你应该阅读有关基类初始化的内容。作为一个提示我会在您的（有点奇怪的）示例中说，您可以尝试使这种语法有效：

mPayment m(mort1);

Answer 2

您正在使用MortgageCalc mort1; mPayment m; tPayment t; iPayment i;等所有不同的对象。这些对象没有任何关系。

示例：

mort1 = {term, monthly, total, interest, years, loan}

并假设您已使用1

进行初始化

mort1 = {term=1, monthly=1, total=1, interest=1, years=1, loan=1}

但它不会影响m，因为它们都存储在不同位置的内存中。

m = {term=0, monthly=0, total=0, interest=0, years=0, loan=0}

您可以检查两者的基本地址是否为cout<<&mort1<<endl<<&m;。

您设置的数据成员属于MortgageCalc mort1而非mPayment m; tPayment t;。

你需要刷新你的C ++基础知识。

初始化类函数但输出仍为0

2 个答案: