Question

我正在尝试使用getDate()调用函数pass by reference。在函数lessThan()中，来自object的所有变量都很好，但是在调用对象的函数时出现错误。我为什么要这样做？

错误讯息：

此对象具有与其不兼容的类型限定符成员函数“CDate :: getDate”对象类型是const CDate

ThisCopyNFriend.h：

#pragma once
#include "Header.h"

class CDate
{
public:
    CDate(int, int, int);
    ~CDate();

    void getDate();

    bool lessThan(const CDate&);
    bool equal(const CDate&);
    bool greaterThan(const CDate&);

    CDate plus(const CDate&);
    CDate operator+(const CDate&);

    friend void greet(string);


private:
    int day, month, year;
};

ThisCopyNFriend.cpp：

#include "ThisCopyNFriend.h"

CDate::CDate(int _day = 1, int _month = 1, int _year = 1990)
{
    this->day = _day;
    this->month = _month

;
    this->year = _year;
}

CDate::~CDate()
{
}

void CDate::getDate() {
    cout << day << "/" << month << "/" << year;
}

bool CDate::lessThan(const CDate &_cdate) {
    if (_cdate.year < this->year) {
        cout << "\n  ";
        _cdate.getDate();                // This is the bit that start to have error.
        cout << " is less then ";
        getDate();
        return true;
    } 
    else if(_cdate.month < this->month && _cdate.year == this->year) {
        cout << "\n  ";
        _cdate->getDate();
        cout << " is less then ";
        getDate();
        return true;
    }
    else if (_cdate.day < this->day && _cdate.month == this->month && _cdate.year == this->year) {
        cout << "\n  ";
        _cdate.getDate();
        cout << " is less then ";
        getDate();
        return true;
    }
    else {
        cout << "\n  ";
        getDate();
        cout << " is less then ";
        _cdate.getDate();
        return false;
    }
}

打开任何有关我的代码的建议!!!

Answer 1

在C ++中，＆＃34;限定符＆＃34;表示const（或很少，volatile，但通常不是）。因此，错误消息表示对象为const，但CDate::getDate期望非const对象。要解决这个问题，你应该告诉编译器getDate实际上没有修改它所调用的对象，只需要void CDate::getDate() const而不是void CDate::getDate()。< / p>

在C ++中通过引用传递对象

1 个答案: