为什么我的计算结果不对？

Question

我几乎完成了这个程序。我想我唯一的问题是我的计算。我的数字完全关闭了。我太新了，无法发布图像，所以这里是我的输出的链接。示例：http://imageshack.us/photo/my-images/62/16902078.jpg/

NumDays.h

#ifndef NUMDAYS_H
#define NUMDAYS_H
#include <iostream>
#include <math.h>
using namespace std;

class NumDays
{
private:
    double hours, days;
    void calcDays();
public:
    // Constructors
    NumDays();
    NumDays(double);
    // Mutator Functions
    void setHours(double);

    // Accessor Functions
    double getHours();
    double getDays();

    // Overloaded operator functions
    NumDays operator + (const NumDays &);   // Overloaded +
    NumDays operator - (const NumDays &);   // Overloaded -
    NumDays operator ++ ();                 // Overloaded Prefix ++
    NumDays operator ++ (int);              // Overloaded Postfix ++
    NumDays operator -- ();                 // Overloaded Prefix --
    NumDays operator -- (int);              // Overloaded Postfix --

};
#endif

NumDays.cpp

// Implementation file for the NumDays class
#include <iostream>
#include <math.h>
#include "NumDays.h"
using namespace std;

// Recalculation function
void NumDays::calcDays()
{
    days = hours / 8;
}

// Default Constructor
NumDays::NumDays()
{
    hours = 0;
    days = 0;
}

// Constructor 1
NumDays::NumDays(double h)
{
    hours = h;         
    days = hours * 1 / 8;   
}


// Mutatory Functions
void NumDays::setHours(double h)
{
    hours = h;
}


// Accessor Functions
double NumDays::getHours()
{
    return hours;
}

double NumDays::getDays()
{
    NumDays::calcDays();
    return days;
}


// Overloaded operator functions
NumDays NumDays::operator + (const NumDays &a)
{
    NumDays temp;
    temp.hours = this->hours + a.hours;
return temp;
}

NumDays NumDays::operator - (const NumDays &a)
{
    NumDays temp;
    temp.hours = this->hours + a.hours;
    return temp;
}


NumDays NumDays::operator ++ ()
{
    ++hours;
    calcDays();
    return *this;
}

NumDays NumDays::operator -- ()
{
    --hours;
    calcDays();
    return *this;
}

NumDays NumDays::operator ++ (int)
{
    NumDays temp(*this);
    ++hours;
    return temp;
}

NumDays NumDays::operator -- (int)
{
    hours--;
    calcDays();
    return *this;
}

主.cpp

#include <iostream>
#include "NumDays.h"
using namespace std;

int main()
{
    double hours1, hours2;

    //Prompt for the data for the first 2 objects
    cout << "Enter the number of hours for the the object called One: ";
    cin >> hours1;
    cout << "Enter the number of hours for the the object called Two: ";
    cin >> hours2;

    // Define two objects of WorkHours
    NumDays one(hours1), two(hours2);

    cout << "One: " << one.getDays() << " day(s)" << endl;
    cout << "Two: " << two.getDays() << " day(s)" << endl << endl;

    // Demonstrate addition and subtraction operators
    cout << "Three = One + Two: " << (one - two).getDays() << " day(s)" << endl;
    cout << "One - Two: " << (one - two).getDays() << " day(s)" << endl << endl;

    // Define a third and fourth object to be used for further operator demonstrations
    NumDays three(one + two), four;

    // Demonstrate increment and decrement operators
    four = three++;
    cout << "Four = Three++ " << endl;
    cout << " Three: " << three.getDays() << " day(s)" << endl;
    cout << " Four: " << four.getDays() << " day(s)" << endl << endl;

    four = ++three;
    cout << "Four = ++Three: " << endl;
    cout << " Three: " << three.getDays() << " day(s)" << endl;
    cout << " Four: " << four.getDays() << " day(s)" << endl << endl;

    four = three--;
    cout << "Four = Three--: " << endl;
    cout << " Three: " << three.getDays() << " day(s)" << endl;
    cout << " Four: " << four.getDays() << " day(s)" << endl << endl;

    four = --three;
    cout << "Four = --Three: " << endl;
    cout << " Three: " << three.getDays() << " day(s)" << endl;
    cout << " Four: " << four.getDays() << " day(s)" << endl;

    system("pause");
    return 0;
}

Answer 1

那么，你的

operator <<

函数的实现在哪里呢？

您发布的代码不包含任何内容。您已在

NumDays.h

中将其声明为好友

friend ostream &operator << (ostream &, NumDays &);

但是在

NumDays.cpp

或其他任何地方都没有定义它。

显然，链接器告诉您它找不到它。我也不能。

您必须去您的

NumDays.cpp

并实施您的操作员

<<

和

>>

在那里

ostream &operator << (ostream &s, NumDays &n)
{
  // Whatever
  return s;
}

istream &operator >> (istream &s, NumDays &n);
{
  // Whatever
  return s;
}